You have a super nice, beautiful, and efficient truck. It was designed.. and marketed.. as a MPG king.
I don't know any other way to say this to you.
You may have bought the wrong truck...
You are already trying to improve the experience... trading trailers.. spending money to fix the problem with bandaids....
Please load your truck up with all passengers and all gear they would take on a trip.. and go to a CAT scale and weight your truck.
You may find that you don't have the payload to tow a RV with this truck... Meaning you may be looking at an upgrade to a 2500 already.
thanks!
Jeremiah