If you're using EHU you could just use a standard portable ac unit, it's the only effective way of reducing the temperature and humidity, they can also be used as just a dehumidifier and use at home, not the quietest things when the compressor kicks in but used to cool the van before bed and then just using the fan setting. Had a quick Google and this looks like a bargain to me;
Portable Air Conditioner MZKA780 White incl. Remote Control in the DeubaXXL online shop. Free shipping ✓ Buyer protection ✓ Order online now!
www.deubaxxl.co.uk