Hi Chaps thanks for the replies.
Yes Rhino i have looked at the Pure Freedom system - i already have a 24v booster pump for my RO but i don't use it as my tap pressure is fine - can fill 450L in about 7 hours or so.
The reason im looking at alternatives is i want to do away with all this overnight filling malarky, and also want to move house, and don't want to be tied down by having to consider where the van can be parked for overnight filling etc
Looking at twin DI set up with prefilters also.