Installed the seat in the fuselage. Drilled outer holes on the bottom rear hinge (the one hidden behind the seat) first, to set the geometry, then removed seat and drilled the rest of the hinge using a carpenter's square to keep it straight.
Then reinstalled the seat and drilled the forward and rear upper hinges. The lowered seat makes those hinges flush right up to the edges of the spar channel and the crosstie, but it fit pretty well.
