Match-drilled the subpanel seal support angle to #30, deburred, scuffed, degreased, primed, and re-cloed in position. Using a bucking bar with a hole for short post and Universal head rivet set, back-riveted the angle to the subpanel. Had to use a couple of MSP-42 blind rivets for two locations that were too tight to squeeze, buck or wish.
Reasonably content with the overall task, but thnk that sealants and gaskets will be less than perfect weather seals in the best of conditions.
NOTE: Line on blue painters tape indicates the NOTHING IN THIS AREA due to the canopy frame.