You said you checked the spare tire, did you lube the mechanism? I fluid film mine a minimum of once a year but spring and fall is better. It's not fun if it locks up. Also lube all the door pivot and latch points especially the hatch latch. May want to pull of the inside cover to lube it really well. While in there lube the rear window track and cables plus make sure the drains at the bottom of the door are cleaned out.
You mentioned undercoating, if in any climate that gets the road salted then oil the inside of the frame. Being in Alabama I assume this is a non-issue for you.
One more thing, sit in it with the radio on and day dream.