If you decide against the vinyl tank cover, there is a couple other possibilities that may help.
If the propane tank tray is held on with self tapping screws, and there is enough room between the tank cover and the trailer, you could move the tank tray back a little.that may give you enough room. Make sure your batter won't interfere either. If it is welded on the trailer frame, rule this option out.
The only other option is to replace your wdh shank with a longer one. That will move the hitch head back, resulting in more room between the trailer jack and the rear of the tv.
Here is a link to the shanks E-Trailer carries. Measure your current shank between the 5/8" pin hole and the verticle holes where the hitch head bolts on. All you need to do is swap the hitch head over to the new shank. Keep it the same height and same hitch head angle. Your local dealer may have a longer shank, and you could possible trade the old one in.
Here is a pic of the two shanks. There was a mix up with the dealer ordering the correct shank, so they shipped it to once it came in. Our tailgate would not open all the way because it hit the tongue jack with the shorter shank, but once I swapped out the shank there is plenty of clearance between the tailgate and tongue jack. There is about a 4" difference in length. You may be able to find a shank that gives you enough clearance without being super long.

Most (if not all) of the hitch extensions should not be used with a wdh as far as I know.