For reference sake, here's what I started with:
Once the stringers were all done and the fiberglass had three or four days to cure, I wiped everything down with mildly soapy water using a very rough "paint stripping" level Scotchbrite pad. I had the boat up in the air for this so all the water would run out the bilge drain (my boat sits nose down on the trailer - very irritating).
I then let it dry for one night, then went back at it the next day with a vacuum and then wiped it all down again with acetone. Once the acetone step was done, I mixed up about half a quart of Interlux PrimeKote with the activator/hardener (it's epoxy, after all), then thinned it about 10% with acetone. They say on the can to only use their "special" thinner, but acetone worked just fine for me.
When applying with a brush I had to be diligent about getting it into all the nooks and crannies, but this entire step was all too easy. The toughest part was the fumes. Luckily it was warm out so I had a breeze in the garage.
After the first coat, I followed the instructions on the can and went back for a second. The second made things extremely bright and covered up any thin areas. This stuff is great - doesn't run and goes on quick. Here's a picture of the bilge after priming:
I about flipped out when I was done. It looks like part of my boat again! I even coated the inside of the drive hole, just to be cute.
I waited three days and sanded the white primer with 150 grit paper, then blew it clean with compressed air, wiped it with acetone and applied the first coat of BilgeKote. Here's the finished product:
On to the Next Step: Fixing Stress Cracks