The way I currently have it laid out, Rena having too much sex will eventually knock her out, as she will take damage every time she climaxes (lust bar is filled). So just having sex with enemies won't allow you to progress far.
But there will be a gallery if you want to see the sex scenes from the beat em up portion as well as a "practice" area where you can spawn enemies and set up your own situations. So that way you can see the sex scenes at your leisure.
There will also be ways to have Rena be more sex savvy and more resilient to climaxes/ taking less damage from them. And I'm going to see if I can balance it to have enemies get knocked out after they climax without it being too easy. I'll try out a few things and keep you all posted.