I do mainstream CPA... Im here in case I can learn something from all you dirty adult webmasters
Personally, I would try things like Adult Friend Finder, Fuckbook, Bang Bros, Fling (and other dating) etc... You can also emulate that dudes "GROW YOUR DICK" campaign and send the traffic to boner pills and other CPA offers (supplements)
You could go to sites like YouPorn, Redtube, and Boysfood... then sort the videos by highest rated, and find affiliate programs that way.
I'm not the type to pay for adult memberships, but I can tell you.. the times I have thought about it was because I was like "DAMN, that chick is fuuuuucking sexy. DO WANT!"
From what I've seen most adult affiliate programs aren't very high converting. The amount of money you make is a function of EPC and volume you can throw at it. The holy grail of metrics to track is eCPM.
If youre worried about constantly handing over new affiliate links, you could
1) Get him to sign up with tons and tons of places off the bat
2) Set up your own tracking like HasOffers on a dedicated box, spend the time getting into all the affiliate programs you want to test, and brokering the offers to him