Agree with Yakimabowtie

I would not separate the skins .... it would just make more work & the pieces may
kink or distort during repairs such that they won't weld back together properly.

Cut access holes to the backside of the door big enough to do
the necessary body work. Use a whiz (cutoff) wheel or a reciprocating air
saw to cut nice straight pieces out, so you can tack them back in and
then cover with upholstery after the repairs are accomplished.

I bought a spare set of doors for my panel that had had previous hammer and dolly
work done to them after cutting out the backsides with an acetylene torch! What a mess they made of it! But, its all fixed now and covered .... my dirty little secret!

squire