I've driven a custom camper on a 1993 Mitsubishi Fuso FG 4x4 120,000 miles and a custom camper on a 2004 Fuso FG 4x4 12,000 so far.
I thought the 1993 was perfectly comfortable. A little choppy on I 10 if I had too much air in the rear tires for the load (don't let the dealer set your air...