Pretty much everything that everyone else has covered, but I will post a few things that we carry every trip anywhere, even if it's close to home.
We always carry a spare tire, 2 spare hubs with seals, bearings, and caps. We also carry one of those Half moon jacks, you stick it under the axle and drive forward on solid ground to lift the trailer, it's not the safest thing, but it gets you in and out quicker. Infrared thermometer as others have stated, and the absolute best thing, a 20V Dewalt brushless impact (one of the smaller ones), and an impact socket to fit the lugs on the trailer tire. You will be amazed at how much difference it makes in 90 degree weather.
Fishing is a science, study, experiment, fail, and succeed...then start over tomorrow. Yeah I'm a science guy.
03 18ft Xpress Jon boat Center console 90 HP 4stroke Yamaha Humminbird 1199HD SI
97 14ft Polar Kraft Jon boat 85 Johnson 30hp Lowrance Elite 5 DSI