On the rear bulkhead, I would drill out every other rivet and clean the dimple and squeeze new rivets. Then repeat for the second half. I actually did this on my tanks and it turned out well.
There are "structural" blind rivets available but none that are "sealed stem" like the ones used on the rear attch brackets. Even if you installed a suitable CherryMax rivet, you would still need to access the back side to dome seal the rivet. If you really decide that you have to change those rivets I would install access panels and replace them with solid rivets. After cleaning up all of the dried sealant, I ended up with two or three rivets in the ribs that were tilted with an edge sticking up more than I would have liked. I shaved them and they turned out just fine.
A&P IA PPL ASEL
RV-14A kit S/N 140170