I know they make dual band LNB's (2 TV's - different programming) but 3 - I'm not sure they make any automatic one, but they do make a "point it yourself" model:
Mobile Satellite Tri BandNone of the Satellite manufacturers suggest using any kind of DVR in an RV, due to limitations of the performance of the equipment.
The best state of the art, dual band LNB available for DirecTV SD only, Dish SD or HD, and Bell (Canada) is the
Winegard Carryout G2 Winegard Carryout G2They can be bought online for $568.00 (no tax free shipping)