We went with a off white semi-gloss for the walls, and a gloss bright white on the tub. Make sure you use a good primer first. Also, if you are painting plastic, you a plastic primer first. Or use a paint made for plastic. I used bright White Hard Nose from Por 15. It’s a 2 part paint. Takes a bunch of coats, but is very strong and flexible.
We used an exterior paint for the walls. The thought or hope was that it would hold up better to the heat and moisture. There is lots of debates on what kind of paint to use.
Not all those who wonder are lost.