Here is what I did twice in the past year since hurricane Irma's five foot flood surge totaled our new 40 trailer from last year and now I just recently did it again with the replacement one.
-Back in or pull in and level it side to side using lynx lock blocks or equal. Then level it front to back using the tongue jack.
Once it is all level I put down the stabilizers.
After that I used concrete blocks for piers, (3 on each side)
I tried to get the blocks close enough to the frame by either digging down and inch or so or using treated lumber on top(in some cases 2" x 6"'s. In others 3/4")and leaving a 1/4" on top.
Then I finished by using opposing shims on the top with the very top one pounded in with a rubber mallet.
As I did each one, I used a level inside the trailer to make sure it stayed level both front to back and side to side.
When I had them all done, I jacked each axel with a bottle jack under the "U" bolt on the side where the blocks were and removed the blocks once the tire was off them. I could have left them there, but wanted them out for looks.
Double check them in a few weeks in case they settle
In both cases the trailer is rock solid with absolutely no movement
Good luck,
Jack L
