That tail panel looks easy to straighten, probably easier than replacing it.
Use a Port-a-Power. Put lumber across front of trunk(spread the load) & rig a way to push On the Crease, and move it slowly and hammer a little at a time, where needed. Very rewarding to fix if you've never done a repair like it.
Could also repair with a pin welder & slide hammer(a newer method). Also moving metal slowly.
Old time body men would fix much worse, but as labor rates went up the business changed to be a parts replacer instead of repair business.
Hardest part probably behind bumper. Trunk lid much harder repair, due to internal structure, but doable , especially with pin welder method. Easier to get another lid so you have it to test fit to be sure opening is the right width before paint.
Could also Port-a-Power across back of opening to spread it, & slowly hammer(and dolly)or slide hammer the crease & other low spots that develop. Port-a-Power will be in the way. Once again least pressure you can use to move the metal slowly.