You can go here to find a CAT Scale near you, or on your route sometime.
I was able to get a pseudo 4 corner weight at my local scale by going thru for axle weights and immediately going thru again with my right tires off the scale as a re-weigh and subtract the latter from the full axle weights for individual weights. The scale must have enough room to drive over with right tires off the pads and you should check inside before you do it to see if it is allowed.
Check for YouTube videos on how to do CAT scale weighs.
Make sure you are fully loaded (fuel, water, supplies, people, etc.) just like you are going camping.