Do you have a tape measure? If you go from center of the front wheel at the point it makes contact with the road and measure the same point on the rear wheel you have the wheelbase. Take a 2X4 across the top of the AC or the highest point on the roof and see the distance to the ground. Now you have the height. That will change with loading, tire age, and springs.
1995 Roadtrek 19 Versatile
1975 GMC Eleganza II