Join a good Guild. Ooops Wrong Forum.
(Sorry, World of Warcraft joke.)
When we had a TT I used to carry a straight 2x4 and carpenter's level. The 2x4 went across the tongue at the frame and the level went onto that. That got me my left and right.
Then I put the level on the floor inside and raised and lowered the tongue jack until the wife called out level. (Yes she does know how to read one.)
Once I got it perfect I screwed the small levels from Camping World to the camper in the left front corner so I could leave the level at home.
(Don't forget to remove the screws and put 3M 5200 quick set marine adhesive in the holes before you put the screws back in.)