So I took the plunge yesterday and sliced the rear upper plate in two. It was 0.250 inches thick, so with the thin, deep saw I used, I'm left with almost an eighth inch on top and bottom. It now aligns fore and aft due to the angle of the halved plate. The torsional rigidity is now restored, and I can use the Taigen quick release also. Much better IMHO than the HL chassis.