"If your activity is not carried on for profit, allowable deductions cannot exceed the gross receipts for the activity."
This is a quote from the IRS publication linked below:
http://www.irs.gov/uac/Is-Your-Hobby...it-Endeavor%3F
The way I see it, if the IRS makes this allowance to make some money through a "hobby" activity, how can the state's Highway Patrol or DOT have the authority to arbitrarily decide whether or not your racing activities are a hobby or a commercial endeavor? If there are corporations involved and your rig is a rolling billboard, perhaps it may warrant some scrutiny. Otherwise, it's obviously a money grab & harrasment.
Several years ago I was returning from a bracket race in Gainesville, FL and passing through Palatka, FL (State Road 17?) late at night, which happen to have DOT scales between the lanes. Passed them probably a few hundred times over 2-3 decades without ever having a problem. But that night there was a roadblock and everyone was checked for a variety of credentials - cars, trucks, trailers, etc. There was a local cop that was actually getting "giddy" about catching me not having a CDL and whatever else! (Dually & 26' trailer.) Luckily there was a seasoned DOT officer that politely asked me to refrain from challenging the local yokle about the situation, said a few words to him and waved me on.