Insulating an MPV

[MLH]

After much toing and froing ive settled on a Ford Galaxy for the work vehicle. I'll be looking at sleeping in this for 4 days a week (i work nights) which i dont think will be a problem (ive spent the last week in a Z4 as a trial!)

As i'll be sleeping in the days and the tempratures a bit higher i wasnt too worried about insulating it but just by the off chance i ended up working days somewhere i could be looking at a few cold nights.

So i was wondering how would i actually go about improving the insulating qualities of said Galaxy?