Thanks for the advice guys. I think going to do both. Ratchet strap and some sun (once the weather warms back up anyway) and once the shape is right I may make it permanent with some reinforcement. I already have some other area I want to reinforce anyway so the trunk lid will get added to the list.

Maybe I won’t have to wait though. I’ve got 1000w lamps I use to warm my water pump shed during freezes. I bet they would help it get warm to pull into shape.