You can put water in the trailer, just wait until you get to where your going, or at least close and fill there. W
ith a water tank behind the axles, one on top of them, a bumper rack with a genny on it, it sounds like too light a tongue weight was the main issue. Load as much of your heavy stuff in the front of the trailer as you can, travel with no water in the fresh tank and fill once you get off the highway at a gas station or someplace like that. Your hitch may have solved the problem pulling it home empty but if weighed down in the back end again, I'm gonna bet you get a similar result.
Heavy stuff up front and getting the tongue weight in that 12%-15% range with the trailer level to nose down will solve it permanantly.