My phone lights up when there is a reply, I am going to have shut that off. Not sitting here just waiting.
Sure there would be trade offs. And your bus is already done. But not everyone's application is the same, while you live on yours I am looking at more of a mobile hunting cabin with bunk beds that we might take to some NASCAR races.
If I remember correctly after a 20in roof raise, you got the walls and ceilings to somewhere around R20 with 3 inches of professionally sprayed in foam insulation at a cost of $2200.
With 3 times the heat on a new installation, cutting back on some of the insulation cost, it might be a wash.
I think your bus looks sweet , but I still can't tell what is holding up the roof before you put the spacers in on the pic of it in the garage. I think I see some scaffolding in the front but it looks like the whole back end is open air.