The two fetishes that give the biggest chance of failing that enslavement check are Pregnancy and MILF, so if you keep those low, you should be able to resist her more often. A safe way to get Sex EXP is to just fuck normal Goblins in the village for free, since Fetishes cap at Level 5, you can continue stocking up exp without them going up any more and then just lower those two to zero before working at the Brothel again! So it is quite possible to work the Brothel safely even with Pervert and Submissive Flaws, just a bit more tedious.