bodog is OK for pot limit O8, but their fixed limit games are almost always empty. OnGame has people constantly playing in the 25c/25c PLO8 game right up to $1/$1. I dislike their blind structure - two big blinds, wtf? Full Tilt and Stars are by far the best for your kind of games, I have been searching for these games too and nobody comes even slightly close to competing. I think if you want to bonus whore you should play holdem on a dealt rakeback deal (so you don't have to put money in the pot to earn rakeback, just be dealt cards). I think one of the reasons you can't get a decent rakeback and bonus deal with Stars is that they offer far too good a service and they know it, to be throwing money away to encourage people to play on their site (they already have arguably the most players). You can get 27% with Full Tilt but thats not great, although its why I prefer FT to Stars.
Seriously you won't find anywhere near as many FLO8 or Stud8 games on any other site. I think its a case of choosing between a good bonus deal and a top quality website, but then again Full Tilt did give you 100% up to $600 (damn I wish I deposited more than $250)!
AFAIK the Merge network offers HORSE and so does the Action network and so does the Absolute network. Absolute will be your best choice, they have more traffic than the Merge and Action networks, you can get 30% rakeback, 100% up to $500, and they offer a wide selection of games which are usually (albeit sparsely) all being played. Trouble is their tables look visually sickening! Shop around. I think maybe the iPoker network has some games going too, and you can get rakeback and a decent bonus with them. As for Microgaming, they have the PL games too, but Stud 8 and O8 fixed are uninhabited, with no HORSE.