Robb, I wouldn't suggest to bonus grind FTP below 50NL... 25NL, if You can put in at least 30k hands / month.
Anyway... @ 5NL /10NL most of your money isn't coming from rakeback either. Bet your good hands hard, and don't even bother with any fancy plays, and you should be well above 5ptpp/100. Rake is definitely beatable.
If you stop calling and reraisin