I recently purchased a Dezl 560LMT, which is a new Garmin unit that has RV and trucker profiles. I used it on the Race Across America, and it worked pretty darn well. When in RV or trucker profile mode, it won't tell you to make U turns, but will route you in such a way to get you back on course without. It also doesn't say "recalculating" every time you decide to ignore it!

You can enter vehicle height, axle weight, length and several other parameters that aid in the routing.

Ray