Need info - replacing 16.5 inch wheels and old style tires.

[CCCC]

In the process or renewing a 1970 GMC 3500 (with utility bed and nice Alaskan Camper mounted) and want to go to different wheels/tires.

The factory setup is single rear (not dually) and the original front wheels/tires are 7.50/16.5 and the rear are 12/16.5 (quite wide). The load range on those tires is "D".

I would like to go to 16" wheels and have the same size wheels/tires on both front and back, but figure that the original owner had those wider wheels/tires on the rear due to weight of the ute body and camper. The camper weighs about 1500 lbs. and the ute body probably 2X (more?) the weight of a stock pickup bed. That rear weight is probably about the same as the old style pickup bed mounted camper setup.

If I were to go with one wheel/tire type, say 8 inch wide wheels with 235/85/16 tires in load range "E", would such provide sufficient load capacity without worry about overload? Or. need I to go to wider wheels and load range "F" tires due to the rear weight?

Experienced advice will be appreciated. Also, is there any market for very good used 16.5 wheels of the two sizes noted above?

Thanks.