To get from I-80 to I-70, you could take US-50 (The Loneliest Road). This is a better way than going all the way to SLC and backtracking down I-15. Get off I-80 in Fernley and take Alt-50 to Fallon to pick it up. Do not leave Fallon without a full tank of gas, there's gas in Austin but you don't want to pay the price if you can help it. You should be able to make it from SF to Ely in one day, it's an interesting place to spend the night. You could stay at the Nevada Hotel and go across the street to the Jailhouse Steakhouse for dinner. Fill your gas tank again.

Stay on 50 and it will put you on I-70 in Salina. Fill your gas tank there, the next services are over 100 miles on I-70. Your next overnight will probably need to be in Glenwood Springs.