Towing with 1/2 ton within its design limits are fine and I have done with Chevy 1/2 ton and 6,000 TT and was a great experience.
I will say though that upgrading the tires to LT tires and adding heavier suspension and etc on lightweight 1/2 ton like the Heavy Payload Option does probably isn’t a great idea. My neighbor had a 2014 Heavy Payload option and road like a lumber wagon. He took my GMC 1-ton diesel out for the ride and couldn't believe that the ride was that much better the F150 Heavy Payload. Even his wife could see a noticeable difference between the ride of the F150 and 1-ton diesel and the on GMC 1 ton being much more civil. Shortly after that, he traded for Standard F150 since all he tows in utility trailers and Jet Skis. The standard F150 road a lot better than my GMC 1-ton but that is to be expected.
I took the tour of the F150 plant in Kansas City with our Chamber and I ask the question why they don't put the EB 3.5 in the Super Duties. He stated the EB engine was a great engine but it will not hold up to the demands put on the Super Duties trucks. He said contractors will max out the capacities of the truck on day one and expect it to handle that load day after day for 250,000 miles and the EB just isn't up to the task. He said for customers that we target for the F150 EB it will that only max it out on occasion it will last the life of the truck.
Again a properly matched/setup 1/2 ton and TT will do a great job but that limited your selection of RV to the light side. If you want to tow heavy get the proper tool.