I have to tell you... one of my companies sells that bubble foil. I've come to realize that the benifits of this stuff is huge. The "R-value" isn't great, but it is hard to argue that it reflects an incredible amount of energy. It is amazing in steel pole barns that gain heat. I've never seen it used in a bus, but I certainly plan to use it, both in the roof and the walls. Reflecting the sun's heat out in the hot summer sun is the biggest part of this game. I did a work shop recently for my previous home. It had 4" walls. I simply stapled this bubble/foil/bubble to the walls with a 3-1/2" fiberglass inside the studs. It turned out that the shop could be heated with very little energy.Enough of my sales pitch
As to the heat strips-all three of mine have them. The trick is to close the vents to slow down the air speed, and they do work-but take about 5 minutes to warm up, so in the meantime have cold air swirling around-which can be irritating.