I guess it all depends on how far you're travelling. I don't want to drive 300 miles to a 3 day race and have to turn around and come home on day 1. I have a large rolling toolbox that gets bungeed in the front of the trailer. Most of my tools are in it. I roll this into my shop when the car comes out. Floor jack, jack stands, impact wrench, fender covers, wheel covers with magnets in them. Tarp in case I need to adjust something underneath. I carry extra Holley bowl gaskets and gaskets for adjustable needle/seats. Shop towels and hand cleaner. Marking paint for ET changes, cover for shift light, some kind of weather measuring device, at least for temp and humidity. Portable radio for track announcements in case you can't hear the PA. Box fans for cooling the car AND you. Spare trailer tire. I need a laptop if I need to change timing on my setup, so I bring a Surface Pro along. The little flashlights on a headband are fantastic after dark, I wouldn't be without one! Mosquito spray!
