After this last weekend's positive experience with a coleman xtreme
cooler in 100F+ temperatures, I'm wondering if there's even any
reason trying to fix up the Dometic.

First question -- has anyone ever had a working dometic provide
adequate cooling in 100F+ temperatures?

Looking at the coleman cooler, I notice that it has almost 2" of foam
insulation.   Looking at the dometic, it seems to have very little
insulation, and it also seems to be self-defeating as it dumps so
much waste heat under the cabinet, so it's basically bathing itself
in hear.

Second question -- is re-insulating the dometic with some sort of
modern insulator a possibility?

Third question -- does venting the waste heat out of the van make a
serious difference?  The dometic has a fan already, but all it seems
to do is stir up the air behind the cabinet.   Would a fan that vents
the air outside of the van actually be better?