I don't use X chocks, I use these BAL locking chocks for between the tires. Get 2, one for each side.
Note the larger surface area that grabs the tire. I have never had the trailer move at all with these in place. They are the first thing I do after the trailer is lever side to side and the last thing that gets removed prior to departure. Use these and big blocks under the tongue jack and you won't have any issues.
I stopped using those wedge chocks years ago, they are worthless unless you are on pavement.
