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.)
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW