Until more is known this is my best advice. This is from RV Basics
To properly weigh the trailer your propane tanks should be full. If you plan to travel with fresh water onboard the fresh water tank should also be filled to the level at which it will be when traveling.
Hitch up the trailer and go back to the scale. Drive on just far enough that only the tow vehicle (still with full fuel and passengers) is on the scales and get a weighing. This weight minus the tow vehicle's weight equals the hitch weigh.
The tongue weight of a travel trailer the range of 10% to 12%. For a fifth wheel, the hitch weight should be more in the range of 20% of the fifth wheel's weight. Of course, at no time should the weight exceed the tow vehicle's maximum rating.
Now drive the tow vehicle and trailer fully onto the scale to get the Gross Combined Vehicle Weight. This weight minus the tow vehicle weight equals the trailer weight. The Gross Vehicle Weight Rating (from the manufacturers sticker) minus the trailer's wet weight equals the amount of supplies and personal gear you can load.
If you have dual axles on the trailer you can get a weight for each one by stopping with the first axle on the scale and getting a weight. Then drive all the way onto the scale.
Weigh masters are accustomed to this procedure and as long as you discuss what you're trying to accomplish they will work with you.
