Pull up on scale and weight front axel, than all the way up and weight with both axels on scale, than pull forward and just weigh rear axel.
This gives you front axel, total weight , and rear axel weight.
ideal is to weigh all four corners at same time, This takes individual scales like the troopers use.
There are places to get 4 corner. Usually at a RV rally.
Back in the 60's Window Vans were popular. We had one it was a DIY.
Bought the Dodge van brand new. When I ordered it. Only had front seats and one rear bench seat.
Wife made drapes for the windows. I put plywood floor down with carpet.
I also out foam insulation in the walls and paneled them.
I had a rear engine heater for the kids when on the road. A wall folding cot. We traveled all over with it.