Welcome! Dig around on some othe threads around here and you'll find quite a bit of info. A lot of the info is geared towards smaller gasoline cars, but many of the same principles apply to a big diesel pickup. What year is your truck? 2wd or 4wd? Auto or manual tranny?
Also, since you have that big enclosed trailer, you might want to look into one of these tails that were designed for big rigs, but could probably be adapted to your trailer:
