Sound deadener questions?

[muddpile]

I'm getting closer and closer to finishing this truck, and the more I think about it, the more sound deadening has me worried. I had to replace a LOT of rust (see my build thread, it was bad...) and with this stuff stuck all over it, what happens if it rusts again. I did my corvette with it, and it worked GREAT, but it's made of fibreglass so rust wasn't a concern. I suppose the truck was driven in winter, on gravel and stored outdoors, so that's where the rust came from, but it still is a concern of mine. What do most of you guys reccommend? I don't have an in-cab tank anymore, and will be building a rear cab cover. I have 70 Square feet of brown bread sound deadener from B-Quiet. Thanks!