i'm in a first floor flat and run the hose out of the utility room window across the garden and into the van 
same
4040 ro in cupboard above hallway window, waste straight out wall and into drain, pure goes under floorboards to my front window, ziptied to downpipe to ground floor, connect up a 50 meter reel of 1/2/" hose and feed it out to van.
If I were fortunate enough to have mates and family not on water meters I would have had the ro and di on the van and just filled up at there houses.
Either way I think the most important factor for me was the speed and the quality of the water i could produce and so would recommend getting a 4040 such as the hf5 from gaps.