http://www.obrienscamping.co.uk/article ... nstall.htmI think you will be hard pushed to find a fridge which doesn't require side vents.
Maybe possible to extract the exhaust under the van but the heater exchanger on back will struggle even in cold weather without adequate ventilation.
If you could create a sealed space around the fridge and use a mounted fan like below to pull the heat away from the fins and have holes in floor with fans pushing air in and another for pulling air out with a pipe extended to the heighest point... might be possible...
However, I think the fridge will suffer poor performance and you will also be constantly drawing at minimum 0.15amp per fan, so looking at the minimum of 0.6amp constant draw with fridge operating. During winter theres only 6 good hours of sunlight from solar power, the other 18hrs will draw over 10amps... nothing serious if you live on hookup all winter but even with 100w solar panel, cloudy winter day will only produce about 0.5amp from solar power.

Livin' in me van in Portugal.
'93 Mk4 TD 150L Hitop Custom Camper
100ps Epic blue spot