Toby,
Drilling the ends of the struts and gluing wires (I use stainless steel guitar wire, many here use brass) and having a corresponding hole drilled in the fuselage where the strut attaches, then gluing it all in place. The advanced Kits like Wingnut Wings usually don't require this treatment as the struts are well engineered at their attachment points. Something you may want to consider as it really helps in the assembly process and certainly adds strength to the model. I'm building the Roden Seimens Schuckert DIII in 1:32 presently and it like your SE5a has very simple "Butt" joints for the cabane struts. I just finished "pinning" all the struts including the landing gear to save my sanity when I assemble it shortly!
Cheers,
Lance