[alanw]

I've dealt with some minor bulging, nothing that bad though. A heat gun is not too extreme if you are careful, just heat evenly. Try exposing the affected area to the sun first before resorting to the heat gun, that should soften it considerably (the darker the color the better). Even a dark blanket over the area to absorb sunlight and heat the plastic below should work. You should be able to get it to move.