I've done the stupid stupid on a few occasions. Haven't towed a 5 ton but have about 2000 white knuckle miles towing deuces behind my 1 ton crew cab. I strongly advise against it but if you must, take this word of advise. Take as much off the towed vehicle and put into the towing vehicle. It is still a recipe for disaster but here's how far I've gone trying to do the wrong thing right. First take off the outside duals and spare and load them into the towing vehicle. Next pull all 4 rear axle shafts and do same. If it has batteries, put them in the towing vehicle as well. Aim the towbar down slightly at the front if possible. This adds a little downward leverage during crisis braking. And for Gods sake and lifes sake, don't knowingly set yourself up for crisis braking.
Bottom line is heed my words, for 50 miles, suck up the cost and have it towed. Another thought would be to use a deuce. At least the deuce can apply the 5 tons brakes if they work.