A friend had a Toyota mini-motorhome (circa mid-70's) that was a dually. It looked like a stock rear axle with special rims. Each special dual rim set-up appeared to be made of one stock rim/center section (inside) and a second rim (sans center section) welded to a circular spacer. I think the chassis had larger springs, shocks and anti-sway bar. A good machine/welding shop might be able to make you a set out of steel Ranger wheels. I say GO FOR IT!