On my 64 cab the outer top skin of my roof was a mess and I have to replace it. Since I have the sheet metal off I would like to put some insulation between the outer and inner cab roof skins. I noticed that the only thing that was there was a small piece of tar paper. Would peel and seal work or would it sweat and build up condensation? I have done a search on peel and seal and I agree that it will work well on the floors etc. I just wonder about the roof with the extreme heat buildup from the sun.