Just a thought as I am thinking of a solution for us as well... Most water pumps have a bypass already installed for winterization with a short cut hose designed for pumping antifreeze. If one carried an extra 40+ gallon bladder, could you not use a full length hose off that typically short hose connection and run it to the bladder? Then just flip your valve from the internal tank to the external tank when needed? Anyone see any downside to that concept?
Also, anyone have recommendations for fairly rugged portable bladders? My concern is placing in the bed of the truck puts it next to the rest of my "stuff" and I'd be scared to have something roll or land on it and easily puncture. I would even consider a solid water tank similar to what is in the camper but would obviously want it designed for potable water. Also need to remember to disinfect.
1 more question for everyone... Are the flexible bladder type containers (ideally 50-60 gallons) durable enough to fill at home and travel full fora few hours in the bed of a truck? Where we boondock there are no water fills near bye, so what we bring is what we have. Thanks