I can tell you from experience from when I PCS'd from Fort Lewis, WA to Fort Benning, GA that a stock 1987 1008 CUCV will handle that load and more rather fine over flat ground, but becomes sluggish on hills and drops down to second gear. That trip I weighed in a 13,625lbs and traveled over 2500 miles one way, including through the rocky mountains. Personally, I believe that upgrading the brakes, shocks, adding a transmission inter-cooler, and ensuring the engine is well maintained, will bring a stock CUCV into serviceable condition for what he wants to do.
PS: It was amusing to watch the semi's passing me going up those hills :Wow1: