Storing my primed truck?

[wibas]

I did not use epoxy under the bondo on my 1952 GMC. I think I have the dolly and bondo work done on the cab and doors. Now I think I'm ready for high build primer and block sanding. My question is after block sanding I will have to stop doing the body work. My truck is stored in my garage so it is out of the weather but I do heat the garage somedays during the winter as I do other work out there. Do I need to apply anything over the high build to prevent having moisture problems over the winter? Should I spray epoxy primer over the bondo before the high build? I'm just learning on this body work stuff. I live in central Wi. so winters are pretty cold but it sure is hot now Thanks for any help!