I corrected the warp in the trailing edge by re-drilling the aluminum angle while the whole elevator was weighted down to the table. That made a big difference and it looks like the edge is very straight now. I applied the VHB tape and got everything stuck together, stepped back to admire how much better it worked this time, and quickly realized I forgot to upsize one of the countersinks in the wedge. While match drilling the holes earlier, I let the drill bit wander just a bit, which made an oblong hole in the bottom skin. Nothing terrible, but a regular 3/32" rivet wouldn't work anymore. I dimpled the hole in the skin to the larger size, but managed to forget to do the same to the wedge. So I had to pull the skin and wedge apart (that tape is amazingly strong) so I could re-countersink the wedge in that one spot. Well, maybe I'll finally get it right the first time when I do the trailing edge of the left elevator.
So now the whole contraption is put together and I'm just letting it sit tonight to see if the tape will adhere for the second time. Hopefully I don't have to clean it off and do it all over again. Considering the tape is purely for ease of assembly and has nothing to do with structural integrity, as long as I can rivet without things moving, I should be okay.
I match drilled the spar, skin and ribs. Even though the underside of the spar and skin are pre-drilled for #40s, they actually require a #30 enlargement since they will use 4-4 blind rivets, just like the right elevator.
The area where the trim servo fits gets a doubler mounted around the hole in the skin, then the plate where the servo motor itself sits is attached to the doubler using nut plates.