Ok, my personal opinion here of course: I would never wax full time, I think its too much work. I am all about selling products which is the least amount of work with the highest income.
I fully understand what you are saying about getting bored and spending money on back bar. Buy retail sizes for your back bar for the things that are the same.
If you follow what you want to do, your clientele will also follow that simply based on exposure. Your facial clients will drop off if you don't put your focus or energy there. You can also simply not take facial clients any more.