My B has only a dinky "Fume Releaser" vent above the loo in the back. Living in Ten-Zillion degree Arizona, where temps inside a car hit 170F. in the Summer, I'm thinking that installing a 14" square (industry standard) vent like a Shurflo or Fantastic would be a good idea.
I have the tools needed, and am not "skeered" of cutting the hole.
Right now, I'm thinking of mounting the vent right in line with the aft end of the cab-over, and in front of the air conditioner..
Being ah..er, "po",, I am aiming to spend as little as necessary to get the vent parts.. eBay is my friend.
Right now, I'm thinking of using a vent and adding a solar-powered fan unit in the vent top that can be on when the RV is not in use. The regular, larger 12V fan (reverseable) can be used when camping. I may mount the solar fan in a MaxxAir cover.
This project won't take place until the Fall, so if you see this post late, please don't think it's 205 to chime in. I appreciate any tips on vent units to use, installation, or links to suitable products. I'm especially interested in anyone's experience with the solar vent fans on the market.