I try to find a way to make a base for rank and file troops, that looks like it was made like all of a piece.
I too have been trying to do this - and I have done some work on it. I should get a picture and share it, once I have fixed the inherent problems with it! But your work looks excellent and very exciting.
I made a large base the size of the unit out of laminated plasticard, with details glued on the top, and then cut it up. But I think I did not weight it for long enough - because the bases have curved and cupped slightly
I am going to fix this by getting some other plasticard and gluing it to the bottom (with a magnet in place, to allow for movement trays) and then use putty to seal the curved edges. The curve will not be a problem, I think, once that is done.