Upper surfaces now wear more than just black primer.
I started the process with a loose coat of XF-53 Neutral Grey, followed by XF-52 Flat Earth over the rib tapes:

Next, I masked the ribs and outer frame using a set of masks I cut on the Silhouette.

Once masked, I sprayed a quick layer of under color: the upper wings got XF-10 Flat Brown, and the lower wings, XF-51 Khaki Drab (with a bit off crossover for both). My goal was to have the surfaces that receive the most sunlight have a slightly browner tint and the more protected areas a more greenish one. I will paint the fuselage in a similar fashion. No pictures at this stage, but the appearance is very uneven and varied still.
Once dried, I removed the masks and sprayed everything with the final PC-10 Mix (XF-62 Olive Drab & XF-10 Flat Brown 2:1 as called for in the instructions). Thin coats, building up slowly until it looks tied together, but the under layers still show through (at least that's the goal).

Side comment: I am finding it fairly difficult to capture a photograph of the "PC-10" that looks like it does to my eye. As is visible in this picture, I next used a light grey colored pencil to outline the rib tapes and "seams" along the edges of the wings. The effect that I was trying to represent can be seen in this photo from James Fahey's (Jamo's) invaluable collection (I hope you don't mind my posting this James, and will remove it if you'd prefer):

The wing on the left shows the pencil work as it looks when first applied, the wing on the right shows the appearance after taking it back with a wet cotton bud. I was afraid to go too heavy with the effect (and opted not to do the outlines of the reinforcements around the hinges, etc.) but, seeing how much a coat of clear matte dampened things, I think I could have gone a bit further with it. Next build....

I think the colors are close-ish in this picture, but the photograph over emphasizes the pencil marks. It is also hard to see the color variation between the upper and lower wings; in person, I can see the brown vs green, but it is subtle enough that I would likely not pick up on it if I wasn't aware of it.
Continuing on, this particular aircraft has now been positively identified:

Aside from the little touch up required in the '8', the masking went reasonably smoothly. I mixed a touch of XF-55 Deck Tan into the X-2 Flat White (1:40) to tone it down a bit. Emboldened, I decided to have a crack at painting the roundels. I don't have pictures, but will describe my process for those interested: I again cut the masks from Tamiya sheet tape, and transferred them to the wing using an oversized piece of clear frisket film. I had taped the ailerons into position so sprayed the entire roundel as a unit: using the frisket film, I removed all but the outline mask from the surface, and put down a coat of the off-white mixture described above. Next, (with mixed success... more on this to come), I replaced the center pieces of the mask, and removed the blue section for painting with XF-8 Flat Blue. For the record, I used a bit of liquid masking agent where the two mask pieces cam together. Once everything had dried, I covered the blue section, removed the center dot, and sprayed red. In an exception to my reliance on Tamiya paints, I used Mr. Color 81, Russet, for this as it looked closest to the decal color to my eye. As I mentioned, I had varying degrees of success in my attempts. I'll go with the more flattering results first (everything will get clear coated and eventually weathered a bit):


There is a bit of bleed around a couple of the rib tapes, and the thin white edging (very challenging in general) is not perfect, but the results are acceptable. On the other hand....

Well... it is a learning process, and there is no better instructor than failure. There is certainly more bleeding on this one, but the deal breaker for me is the misalignment of the aforementioned white border. This was the first one I did, and the process changed my technique a bit for the other wing. Here's what I learned:
• It is easier to place and remove tape off of a gloss surface than a flat one. Not shocking, but it made a real difference. The more you struggle to place and remove the pieces, the greater the odds one of the OMG-#?%!!#-annoyingly-thin ones will end up misshaped. Sorry.
• Do what you can to improve visibility. When everything has a coat of white paint it can be challenging to see how well the replaced mask lines up with its teammates already in place; there is just not enough contrast between the white painted wing surface, and the white painted masking tape. This is particularly true with a bit of glare on the surface of the glossy frisket tape. Prior to placing the mask on the starboard wing, I took a black sharpie and coated the tape in a number of places. Even with a bit of white paint overspray, it was much easier to see the mask edges, and therefore easier to get decent alignment.
• Don't be penny smart. I had issues in replacing the port side mask, but rather than "waste" material by cutting another mask, I attempted to fix the problem by removing and adjusting the creased piece. A single sheet of the masking tape is roughly $1.30 or so.... I'd gladly pay quite a bit more than that to not have to redo the wing now (not to mention the additional mask I will be cutting anyway...) I think my impatience to get results played a factor here as well, but the concept is the same: pay now, or pay more later. Either way, it was a poor decision by me.
I think that covers it. My plan is to sand the roundel back bit so that the edges don't show, and repeat the wing painting process from the last unsullied rib tape. I am hoping to not have to strip the whole thing, as I can't say I want to repeat the lower surface process as well. This is why I decided to paint the upper surfaces prior to applying the CDL decals... hopefully I will put my experience to good use and get two clean lower wing roundels when the time comes!
Anyway, long post, so thanks to those who read through it. Comments, questions, and advice are welcome. If it is interesting or helpful to anyone, I can photograph the roundel masking process (I'm honestly not sure what the pictures would add, but I'm glad to do it).
Thanks for checking in,
Chris