Originally Posted by Sleddgracer
this winter will have to be without foam insulation
I think you must be talking about less cold environments.
I was specifically talking about the arctic conditions in your OP.
Increasing active cross-ventilation and raising temperatures are really the only alternatives.
Except moving to a drier location.
And forget American made RV-style heaters, the Propex and Webasto style are the way to go.
Also units designed for marine use.