My uncle towed well over 10k lbs with a 4.3l S10 from CA (up and over the Rockies). You can tow the Space Shuttle with a K10, if you're not in a hurry.
Personally, I'd dolly the Jeep, install an aftermarket trans cooler, and a temp gauge. That would be your cheapest option. If UHaul has a dolly with brakes.
Are you taking I70 through KS? Or going through TX and up from NM? I70 through KS will be FLAT! Your only real hills will be Monument CO.
Those old trucks are bulletproof, but slow. Take your time, you'll be fine.
Welcome back to CO! And thank you for your service.