Here is how I use a CAT scale--
Go inside and talk to cashier and explain you have an RV and need two weights, without driving off the scales.
Drive onto the scales and carefully locate front axle of truck on first platform; rear axle of truck on second platform; position everything so that landing legs of fifth wheel are just on the third platform--this will put the axles of the fiver also on the third platform. Then call in for a weight. Cashier will let you know when this is done. Then raise the fiver with the landing legs until the kingpin plate begins to clear the truck hitch--DO NOT LIFT THE TRUCK. Call in for a re-weigh. Then lower the trailer, drive off, pay for the 2 weights and you will have all the info you need--axle weights and pin weights by subtracting the 2 rear axle weights.
I also wait til there are no semis in line.
'05 36TK3 Mobile Suites
'10 F450 new to me
'09 F450 Lariat 4x4--died