My unit had a very basic fan in the bathroom. I don't think it would have done much plus the blades were hitting the screen. We dry camp a fair bit so we needed a decent fan.
The Maxx fan has a thermostat, 3 speeds and reverse air flow. It fit nicely in the existing 14" opening. I set it on a base of butyl rubber tape then used Dicor self levelling sealant on the screw heads etc. No leaks!
It wasn't that hard to do but I didn't feel like replacing the forward vent so i just added a Maxx cover.