Would this be a good deal for a roofer or is it a dumb thought
Tearing off yourself is something I (as the roofer) would shy away from.
I come over and look up at a bare roof (or so I think, from the ground), give you a bid and you accept.
I get up ON the roof to find out that it wasn't so bare after all. Nails that haven't been pulled. Wood that is less than acceptable (to me anyway), etc.
Let's even leave the wood replacement out of it. But there's a 1000 nails that I have to pull, either as I go, or before I start.
NOW, I have obviously already thought about this, so am I going to let it happen as I said above? NO....I'm going to raise the bid, at least some, for the possibility of this problem (these problems) occuring. So you're paying full for the install, and maybe half of what the tear off would cost you anyway.
Now throw the wood back in there that I DIDN'T know about before..and didn't order materials for, and you're paying $50/hour/worker while we wait for material to come and there goes the rest of your savings.
To answer your actual question: If you build a relationship with a roofer and pitch this to him and he goes for it, then great...tear off OTHER roofs to pay your debt...but I would personally stay away from doing my own....conflict of interest....you work for the roofer on your own roof...naaa.