This is how I do it. I am not a big fan of unhooking my fiver in a truck stop lot.
At some point while traveling, and full of fuel I weigh my combination. Generally I will go inside after fueling and tell them I am a RVer and I want to run my rig across the scale. They will tell me to go ahead and come back inside for the ticket.
Take it across, they will provide directions on intercom while on the scale. Then park and go inside, pay your $10.00, and get your weigh ticket.
I go on with my travels. It could be that afternoon, or it could be in a week, but when I am unhooked at a CG I will weigh the truck just by itself. I make sure I have just fueled up.
Doing it this way actually costs you the $10.00 two times, but to me it is worth it not having to unhook and hook back up in a truck stop parking lot.