Hi Dave,
This is also something we considered but pretty much wrote off due to price. Your main issue will be the fact the decking does not move but the 'van might. The high pressure hoses for air con do not have a lot of flex in them. In the end we went for a moblie unit and I made a plate for a window so I can attach the hose. Can be a tad noisy though. Even then we still never leave our dog in the van unattended just in case we lose power which does happen on a semi frequent occasion
I am sure someone posted on here about a air con system for 'vans but you'd have to do a search
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