two other thoughts:

1) get a GPS that routes you around weigh stations- truckers have them but they are $400+ - maybe cheaper but I've never shopped for one with that feature.

2) If there is 1 or 2 weigh stations that you'd pass frequently, drive there in your car (when they are open...if you know when...) roll up and ask the weigh station operator-guys in person. Be sure to wear clothes similar to theirs (no suits or dirty overalls), don't approach the place if they are busy. Tell your story the way you told it here, and be up front with them- give the people in question a chance to tell you what is up. Maybe don't talk to the guys in the booth - maybe talk the policeman sitting in a cruiser next to the booth. Unless they are having an unusually bad day, they'll at least give you a better informed/more local opinion that you'd get on any internet.

If it were a power plant, I'd tell you to bring a box of donuts or Bagels - use your own discretion here - Cheese curls ? Packer's Jerseys ? Good Coffee for their coffee-maker ? soft-multi ply toilet paper ( 50% serious - institutional toilet paper is always the brunt of sandpaper jokes...but perhaps I'm oversharing here =) Anyone who has ever worked for the .gov will agree with me here.

...you get the idea. $12 in donuts is well spent if it saves you hassle down the line

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