Thanks for all the input everyone! Deerfield I would agree the caddy would be tough to move around. Almost impossible to get it back in the truck by yourself. I think I will look at siphons at Walmart first, but I'm leaning towards the offroad jugs and fill hose with valve. Maybe I'll make my own fill hose based on the distance between the fill hole on the boat and swim platform/rear cushion. Thanks again for the ideas.
Kurt