I need to spot paint my masts whilst they are down, but the minimum temperature needs to be 15c. I am proposing building a heated moveable tent which I can slide along the mast as I paint it. The tent is really a small structure made of gash wood and I thought to maximise insulation, this could be covered in bubble wrap. I did not appreciate there were 2 sizes of bubbles in bubble wrap - big and small. My question is, should I go for the small bubbles or large bubbles to maximise insulation?