I'd say the best idea is the wrecker. However with the motor home towing and someone operating the propeller brake as Ralfy described you should be OK for 5 miles.
I'm glad you realize your half-ton won't handle the job. If any of you people haul big trucks on little trailers with no trailer brakes using half ton trucks, you are nuts. I hope I'm not in your path when you try to stop that load.