Just a note on Tires on the Truck you're Looking at:
On my F150 Supercab- A lot of 1/2 Ton trucks come with PS rated tires. I replaced mine with LT Michelon's (About a $1200 bill for 4).
They are a stiffer tire and after replacing the PS tires, I get a much better ride towing the TT. With the PS's they seem to be much squishier going down the road, leading to the Truck wondering somewhat.
The LT's seem to keep the Truck more in a straight line. The LT's also can be inflated up to 80 PSI when towing and lowerd down to 50 when not towing. I inflate the back tires at 70 lbs and the front ones at 65 lbs, when towing the TT.
The reason why Manufacture's put PS tires on 1/2 tons is for a smoother ride. but they don't tow as nice as the LT's. But then again ,someone may not agree with my accessment??
It is also important to keep the trailer tires at near max as what is stamped on the tires. Also, hope you have some good tires on the trailer- but they are probably "China Bombs" as many RV'ers refer to them as being (But that is another topic of Discussion?)