Update: flap in the foam around the water heater?

A great idea. You've analyzed the situation, weighed the pro's and con's and decided it might be a good solution for you. Go for it. If you find it costs too much gas, or the area gets too hot to sit near it, you can always go back to what you have now.

More people should do this type of "out of the box" thinking. They'd be a lot happier and much less disappointed with the RV they decided to buy and use.