Welcome.
Here's my 2 cents. That's a pretty comfortable size. We have been using a 19' trailer for the past 10 years. A bit small, in my opinion. I sold it last year, and I want a 23'.
You don't have to stop at weigh stations with an RV. They are only for commercial vehicles.
You have a class IV hitch receiver.
http://www.courtesyparts.com/nissan-...owingGuide.pdf
Just make sure you use a Class IV weight distributing hitch.
The rear differential is the same in all Titans, except for the gearing, and you already have the lower gears with the off road. The only thing you might consider before you tow is, you might want to change the rear diff fluid to a synthetic. This was standard in later models.