1.5 hrs with some more ProSeal and some other related items...  Mixed a batch to try and touch up inside the tank.  I think I might have been using a bit too much of the Part B (black stuff) since I've basically run out of that while I still have Part A...  Problem?  Maybe this is why my mixes have been hardening up quicker than I'd expect?  Have I mentioned that I don't like sealant...

Since I'm out of Part B I may have to put aside the tank work until the new sealant arrives (which I'll probably run out of before finishing the other tank...).

Drilled the hole for the hold-down strap that has to be installed (near the black Sharpie mark on the rib).

Getting my rivnut gun ready to install the rivnuts...

...Only to discover that the holes in the flange plate are too small...  Tried to drill out the hole to size, but using a handheld drill (I don't currently have a drill press (though that may change...)) resulted in a messy hole.  Using a reamer would work better, so I ordered an appropriate sized chucking reamer bit (15/64").

Yet another ProSeal application approach tried...  Small bristle brush with the hairs trimmed down to about 1/4".  Worked OK for dabbing the sealant on rivet heads.  Short of using one of those expensive sealant "caulking" guns, there's no tidy way to do it (that I've found)...