Since the trunk pan holds 20 gallons of fuel weight, I decided to address this next. First, cut out all the rot.

Trunk rails look good, but frame rail on pass side will need a few small patches. Probably should have done that first, would have been easier, but I got impatient to get the trunk patched up. Have some 16GA sheet sitting around, so I cut a patch and got it spot welded in. What would be a good caulk for the seams?

The 16 GA is tough to shape, but easy to weld.