rapid tac is basically the same as film-on, they are all really just baby shampoo before the coloring and conditioners are added. it isn't rocket science like the removers are, most window tinters use ivory soap as it rinses clean.
however removers aren't just making the surface slippery and then being rinsed out, they actually have a chemical reaction with the surface as their job is to purify it without damaging it. one you do whatever you need to do, you can accomplish the same by using isopropanol, which is the main ingredient of isopropyl alcohol just diluted, full strength and a clean rag will also stop static while painting ;)