We purchased a bladder that fit in the back of the 05 Jeep Grand Cherokee. Pulled up to water spigot, hooked up and filled the bladder. Back at the rig we used a Sureflow pump to pump the water into the Discovery. Worked like a champ! My wife has the name of the place we purchased the bladder from. She's not here this evening. I will get the name and post later.
When we where finished we caped it and folded it up. Never leaked. Just had to watch it closely while filling, did not want to get distracted, that sucker would have made a mess if it overfilled and popped!