Thanks!
My main worry is the shaft itself, it's only 5/8'' I think. But I think it's worth a shot. Worst case is the shaft bends or the backplate bends or cracks, either way it should be easily fixable if something does happen.
There's 2 bearings in the backplate, one in the front and one in the back but I'd like to avoid putting bearings (and carriers) in the frame because skipping those allows me to reposition the engine and/or change the angle of the plate if needed.
This is what the back of it looks like, my sprocket needs to be about 3/4 inch from the rear bearing in order to align with the sprocket on the rear wheel.
View attachment 105332
I think I'll try with just the short shaft just to see what happens, maybe shaft straightening or backplate repair would make a nice video too