We are still thinking about adding a Lance 1191 to our RV's but I WON'T do it without a 3500 DRW truck. Our 11'4" lance scale weighing 3842 lbs loaded to travel without a slide out is all our 2500 HD enhanced to a 3500 HD SRW truck can handle. Ford's no different! Ours has handled great for over 70,000 miles and to Alaska and all over the USA and Canada so far but we do NOT ever drive drive over 60 MPH and won't with that much weight on only 2 "E" Michelin at that back tires with 3415 per tire cap and a combined rear wheel weight capacity of 6830 lbs at 80 psi. Loading everything weighty at all (canned goods, liquids, anything, etc) in the TC as low and far forward as we can and the real heavy stuff in the rear seat of our CC truck helps put some of the carrying weight on the front tires. In our case, it adds about 400-450 on the front axle/tires which means it's not being supported by the rear axle and tires. You wllbe way over on your rear tires and asking for a blowout form felxing heat build up and especially in hot weather or hot blacktop as heat destroys a tire's structure fast.
I think you are really taking a very iffy chance by putting the gorgeous spacious heavy Lance 1191 on your SRW F-250. We have always had a min of one TC since 1965 so we have lots of experience with them on trucks and driving so I'm not talikng about something I don't really know about. The 1191 can be fully used with the extra deep sized slideout in and that's huge to us as few slideout TC's of size are. If we didn't like our present Lance so much, we'd sure buy an 1191 and a DRW truck dedicated to the 1191 only. We'd keep our present wonderful truck just for our 5th wheel. Wouldn't have to change our then and at 72+ and getting older, it's getting increasingly so harder to do each year.