Rlbuki,
I have a NT 31BDSS, It is similar in size and with 5 of us, there is movement unless I block it up well. I use wood wheel chocks that I made out of 4x6 lumber that fits the contour of the wheels. I place a chock behind each wheel then using the truck, I back up slightly on the chocks and place a chock in front of each wheel. I then roll forward a bit and check that all of the wheel chocks are secure. I then lower the tongue jack and disconnect the truck and level out. Placing wood block under each stab jack pad, I then slightly lower the front of the trailer and lower the rear stab jacks until they are set. I then raise the tongue jack slightly and lower the front stab jacks until they are secure. If I have done it right, I usually have very little movement in the trailer even with three kids bouncing around.
I will check the chocks and maybe snug up the stab jacks daily if necessary, if any settling occurs on soft ground. I usually use 1 or 2 4x6 or 2x6 wood blocks under each stab jack and the tongue jack to help reduce the amount that I lower the stab jacks. I have the most movement, if I have the stab jacks nearly fully extended instead of using blocks to build up the distance from the jack to the ground.