There could be a problem with adding jacks behind the wheels depending on when you use them. As long as you level left to right before dropping the landing gear you should be fine. Just adjust the leg extensions to match the already level trailer in relation to the ground (one may be extended further than the other). Just like if you had to put one side up on boards.
If you unhook first, your front legs are already set at whatever angle the ground is and then you jack one side up, you can easily bend the frame.
A complete one touch system would be the best way to go, but you can do the half step of two jacks as long as you keep the right sequence of events.