Weighing a fifth wheel at a CAT scale is easy. Even easier if you're a smart phone user and use the "Weigh My Truck" app. It saves you from the stretch to push the call button and the difficulty hearing over the intercom. I didn't get out of the driver's seat at all for a set of weighings last week.
How to weigh at a CAT scaleHow to weigh on a single scaleIf you weigh at a CAT scale, I have a calculator that makes it pretty easy to figure out weights:
http://towingplanner.com/ActualWeights/FifthWheelCatScales/