My first question would be, is there water close by your camp? In other words, can you fill a bladder or jug within a few miles, or will you need to bring all that water from home? I wouldn't want to truck a full 45 gallon bladder too far, but a few miles just to get back to the trailer would be fine.
I've seen the bladder work well for other boondockers. One guy put it on top of his camper shell (he wasn't in a fiver) then filled it at the other end of the camp. He was able to gravity feed his trailer that way. I was amazed that his shell handled it, but I guess it did. But usually you will need a transfer pump.
I keep a 7 gallon blue water bottle in the basement. When we're boodocking for more than a week or so, I fill that bottle each time we leave camp for the day, and just pour that in the trailer. That way I keep ahead and don't have to make a big chore out of it at any one time. I can still lift 7 gallons, so no pump necessary.