Assuming everyone has full stacks. I don't know how aggressively BTN and SB 3-bet, but assuming they're not too aggro.

I don't play 9-max, but BTN seems rather nitty to me based on stats. So I would iso wider. BTN is likely to fold often to an iso, so it's almost as if we are on the BTN. The BB may call fairly wide, but we'll have position on both BB and MP1 (if he decides to call).

Something like 66+, A9o+, most broadways (except perhaps QTo and JTo), suited connectors down to 76s or 65s, all suited Aces, J9s, Q9s, K9s and perhaps T8s.

You can iso a bit tighter if you think people might 3-bet you more, or if you think MP1 has a tight limping range.

Remember that most of the money comes from recs, so you want to get in there and fight to iso him. The regs may realize that you're somewat out of line, but they won't do anything about it most of the time.

That said, don't go too overboard. If you're not comfortable iso-ing a wider range, there's nothing wrong with playing tighter.