So, you all do realize that we have over 20, 4'10.5" lengths of extruded aluminum 80/20, right? It's 2x2 square, so a bit larger, but it's also probably stronger.
With a little time, you could easily adapt it to the plans.
Their plans call for a 1500mm length as the longest tube. Thats about 4'11", so the pieces we have are just slightly shorter, but should still work with a little adjustment. Or, you could just extend the back plate back a bit and call it good.
As far as the bike bits go, I have a bike I'd happily disassemble for the cause, we'd have to buy a longer chain, but I can cover wheels, gearing, derailer, cables, etc.
So, what I'm saying is, we have all the parts in the space to make one right now. For free. We may need some bolts.
-Deech