michbill,
I haven't been through that many truck stops to give you good advice but, of the ones I have, many have been different in the outside layout. The one I actually used was a truck re-fueling station at Seven Feathers RV Resort and Casino in Oregon. I was fueling the coach and noticed the scales alongside the store. There was no kiosk or, pole or any form of communications on the outside. So, while the wife continued to fuel the coach, I walked inside and asked IF, it was possible for my coach and toad to get weighed and, what would be the cost.
Well, the nice lady behind the counter said it was perfectly ok for us to use the scales and, it would be $7.50 for the certificate. I said great. So, after we finished fueling, we pulled directly onto the scales. The only sign we saw was an LED red and green light at the end. It stayed green until I had the entire coach and toad, correctly positioned on the scale.
Then it went red. Then it went green again. Obviously it meant I was done and time to move off the scale. I then parked the rig and went inside to collect the certificate and, pay the lady. That certificate told me the weight of the front, the rear, combined and, the toads individual weight too.
On one truck scale at a rest stop several years ago, I pulled off the freeway and onto it, a great big ELECTRONIC SIGN said, "move forward" then STOP. Then, that same sign simply spit out the numbers, front, back, combined. So, there's different ways in different circumstances.
Now, if you want to get it weighed at home. There's a couple of ways to do it. One, call or find a local refuse disposal area in your neighborhood and talk to them about getting your coach weighed. Another is, find a moving and Van outfit that may be near you. Most of them have certified scales too. I've used both, several times. The one refuse and recycle establishment at our area in So CAL was $13.50 for the certificate and, the "Mayflower" brand moving outfit charged $6.50 for theirs. So, hope this helps some.
Scott