I would suggest you load up you trailer with what ever you plan on taking to the track, go to the closest truck stop and put the rig on the scales so you know for sure what your "package" weight is. If you are grossly over weight for your rig then you have a problem and your DOT will nail you if you are caught. If you are slightly overweight find som places to lose it in the trailer.

Also make sure you take care of the truck if you are going to tow near it's capacity. No o/d and maybe add an auxilury cooler, and change the fluid often. Deffinitly use the load bars. Good luck and nice truck and trailer!
Steve