I really like idea of this game.
I'm not sure if you know how to do it at the moment but can you turn faces of girls in to assets that can change every encounter. It would reduce feeling that you encounter 3 same girls over and over again. Maybe keep face obstructed during sex scenes so you don't need to integrate them in to the animation. Doggy style is good for keeping face hidden.
Also I'm sure someone there gets off from beating crap out of girls. Not judging it's better to get steam off this way or actually beat someone IRL. Any way for rest of us can you add hostile creatures or poachers in to the mix. Enemies player can beat up without feeling bad about it. If you want to stick with monster girls and not add any animals or monsters. Maybe add aggressive monster girl that has high charm resistance and instantly attacks you without provocation. If she started it retaliation is fair in my opinion. Maybe a puma girl or a grizzly bear girl.
These two are things that first came to mind. Also good luck and have fun with your practice.