http://www.johnhewitt.com/pumps.htmScroll to the bottom of the page and you'll see the booster pumps.
Works well on 450gpd, although if you're using a 450gpd r.o you wont get it down alot more than your 25 litres an hour you're getting. May save 10/15 mins...
Personally id get an ibc if you can and have your r.o producing into that while you work.
Mount it on a couple of pallets so when you get home you can then fill your barrells using the tap (attach a hose) at the bottom.
If you mount it on pallets they'll be no need for bilge pumps, as you're only filling barrels, not trying to transfer water over a distance...