Tankless water heating has always intrigued me.
I looked into it for our main house but ruled it inappropriate here in Northern IL due to the incoming cold ground water temperature.
But in a motorhome, it may have many benefits. Unfortunately what little I have stumbled on, it has its own issues. If only I could recall the details.
One obvious benefit to going tankless, is that OCC increases by 50 pounds.
One thing about our 6 gallon water heater, it works extremely well.... I can't say a bad thing about it, electric or propane, it continues to do an efficient job since 2007.
ABOUT FIBERGLASS ROOFS
Nearly all are glossy textured fiberglass sheathing that is very thin. It is rolled over the left and right sides down a couple of inches to a rain gutter as shown. The only seams are forward at the front cap, and aft at the rear wall. A crowned fiberglass roof is ideal which directs water away from everything including the heavy a/c unit. I have read of people with old weathered fiberglass roofs, reporting in that their fiberglass developed hairs. They talk about applying an RV roofing product to address that.
In this picture, don't be fooled by the full body paint job on the fiberglass sheathing.
I have not seen this in decades, but there was a time when a rare motorhome was made with a fiberglass roof cap that was seamless to about 6" down from the roof.
The best roof is like Coach House has. A 100% seamless fiberglass body which includes the roof. It is made like the hull of a boat. Our 1984 Mirage
SEEN HERE that we owned for 24 years, was made like a Coach House.
We have owned our 2007 Phoenix Cruiser 2350 since new, coming up on 18 years. It's fiberglass roof is like new, but obviously so because we garage our rig.