Towing

Your probably limited by the hitch at 5k lbs. if you weigh the MH you can then figure out what you can safely tow. Since you will probably be flat towing there is virtually no tongue weight. Start with weighing it ready for a trip. If your OK for that weight then look for a hitch rated for 7k lbs.

I ain't saying it's right but came across this coming back from Colorado on I80.

I've seen full sized pickups towed behind motorhomes of varying lengths, so yes it can be done. I'm not sure exactly what you are asking. If you're asking can your motorhome tow your full size pickup, I think you've already answered your own question. According to your posts, you will be grossly over weight and therefore not legal. Could you "get away with it"? Possibly. I just watched a YouTube video of an electric F150 towing a "1 million" pound train. It didn't try to stop it and it was on rails, it also didn't try to tow it up a hill. I'm not the "weight" police so often referred to, but I would say use common sense (is there such a thing anymore?).

There are motorhomes that are properly equipped to tow that much weight. I don't believe most 90's model RVs, especially gas chassis models, are though. There was a major shift in RV chassis design in the early 2000's to address significantly under rated chassis of previous models. The workhorse chassis had significantly higher weight capacity than the P-series GM based models. I didn't keep up with the Ford chassis, but I'm pretty sure almost all of the 90's models weren't up to the task of hauling the coaches built on them. Maybe others have a different experience or more insight into Ford chassis. Again, my experience lies with the GM based chassis. My BIL had a 90's P-Series chassis Bounder. When we bought the 2004 Bounder on the Workhorse chassis, he drove it and the first time he stopped he nearly threw us all through the windshield. His comment was "wow yours has brakes".

What others do or did shouldn’t guide your actions. Thirteen hundred pounds over is too much. That’s not “close.”

is this a one-time thing or will you be doing this on a regular basis? either way someone will likely be along to tell you towing 1400-lbs overweight is ok. i'm not that guy. can you pull the truck? sure. but can you stop as quickly as you could if you were towing nothing or a 3500-lb truck? nope. the brakes on your MH are engineered to stop the GVWR of your MH. even with an aux braking system your braking distance will be dramatically lengthened. you're going to stress the suspension, hitch, possibly the tow bar itself if it's not rated for the weight of your truck. weight ratings exist for a reason. you can probably get away with it once, maybe more, but IMO it's like playing with matches.

all that being said i do have a good friend who towed a park model from northern illinois to northern wisconsin with a 6-cyl pickup. this was 30-odd years ago so i don't recall the specifics but i recall him telling me that it was quite the experience and he was glad it was a one-time thing. we were all young and dumb at one time. most of us survived. my unsolicited advice is the same i gave my good friend...please think twice about doing this.

good luck.