Dealer says mud flaps aren't available for off road

And if you don't have the flares, Weathertech has a set designed for that application.

 

If you plan to offroad, I'd recommend a Floppy style mud flap (search forum for Plasticolor--many members running them and happy with them also much cheaper than OEM or weathertech). The stiff molded mud guards like OEM and Weathertech will not hold up to much offroading. You'll end up ripping them off and probably doing damage to the mounting area.

 

I'll go with those as soon as I rip these off. I had them on my last truck.

FWIW, the weathertechs are shorter than OEM and I think that anything that will rip them off will likely do body damage as well. Time will tell.