Will this rig get me thru the western mountains

We have 2013 Allegro 36LA. Actual length is 36' 11". We tow about 4400. It is V10, 5 Star Tune, 24K Chassis, 5 speed with Tow/Haul. Does great. Live WA and visit family in LA & IL. Done cascades and Rockies. You can do it. 7-8 MPG. I got 12 MPG once,going down hill. I could have gotten better but did not want to turn off the engine. The really steep grades we have dropped to 50. Tow/Haul mode going down hill is a great down shift at the tap of the brakes.