Yes, I agree with you and I plan to do something about that. But I would like it to be a black closed base. So I’m looking for some plastic strips to spray black or similar.
That's great news, it will really set it off nicely.
I would still recommend using 0.5mm veneer (which you can buy in packs from Amazon). This is much stiffer and holds its shape better than plastic strips. I've tried using strips cut from Plasticard and I am currently experimenting with pre-glued melamine edging strips (used for edging kitchen units), and the veneer is my favourite, although it does involve a little more work. But you might want to experiment with a few things and see which you prefer.
I've attached a picture of how I used this on a WWI diorama I was recently working on, I found it was very effective (I painted it black on the finished piece).
