Elko to Mammoth

You don't indicate what kind of an RV you have. I suspect most folks would just go west on IR 80 until Reno then turn left and head south on 580/395 until Mammoth. Alternatives are to head south to US 50 (SR 278 or 305) then to Carson City and then south on US 395. Or from US 50 go south to Tonopah (just east of Austin through the Smokey Valley, SR 376) and then to Coaldale on US 95 and over to Bishop (US 6)and back north on US 395 to Mammoth. There is one huge climb north of Bishop, and one moderate climb (Montgomery Pass) between Coaldale and Benton. Or, if you like hills and some whoops take SR 120 from Benton to Lone Pine and then south to Mammoth on US 395. (SR 120 is a fantastic motorcycle road if that give you some indication what the road will be like. And the whoops are very real.)