some owners report front floor separation due to water tank weight when having camper on jacks only.
I had it as well on my Fleetwood, but it had dryrot damage at the time, so now, even I reinforced the floor with additional steel plates, I always put 4x4 beam under front floor and either cut to length piece of 4x10 or couple of 4x4 as vertical support. That also drastically reduces camper movement