Trailer Aid with a board to lift it a little more, torque wrench, (I set the lug torques to the correct level before camping the first time each season: I needed my impact wrench to get them free since they were all beyond the specified values the first time), a lug wrench to fit the lugs and a 2 foot pipe to extend the lug wrench in case they decide to bind too much for the lug wrench (same one I use to set the WDH) and roadside assistance if all else fails.
Also visibility equipment (triangles, flares, orange vest) rain gear (because that is when it will happen if I don't have it) and a plan in place with the rest of the crew as to who does what and how if an issue arises.
Finally, a good spare. I check all five tires before a long drive for pressure, rot and any other issues (wasp nest in the spare cover can be a real surprise during a trying situation).
2011 PrimeTime Tracer 2600rls
2001 GMC Yukon XL 2500, 6.0L 4.10:1 axle ratio
Nights camping 2014 - 17
2013 - 15