One of the dents (the most obvious) is a centimeter or two long and about 2mm deep and it looks like someone has thumped the car with their fist

I would imagine that it is quite easy to get to the back of this panel (there is a piece of trim that runs up the side of the rear window with a courtesy light in it that I think would pop off quite easily)
I doubt this part of the car is double skinned and providing I can get to the back of the dents what do you think my chances of popping them back out are.
....or do you think I might end up making it worse?

To be honest they hardly notice, except in bright sunlight, and also now that I've spotted them they seem a lot more obvious.

Cheers
-Dan