So that route from Ouray goes through Corkscrew Pass, and then down along Cement Creek?
Corkscrew Pass is about 200 miles from Boulder, through Poncha Springs and Montrose. So that's 400 miles there and back. That would be about $100 in gas. Plus probably another $50 or more actually on the trails between Ouray and Silverton, for
$150 -
$200 total for a trip including some Great Scenery and Off-road Adventure. I would take at least one, maybe two, extra 5 gallon Fuel containers and other stuff. That is still not too bad in fuel cost, even with the prices today. (The reasons for which we probably shouldn't discuss here.)
I would guess there are spots where overnight camping could be enjoyed ... ?
I did some calculations to get an idea of how much more economical my Corvette is compared to my Trail Boss. I am usually getting 18 - 20 MPG in my TB, and I get 23 - 30 MPG in my Corvette. The 87 octane for the TB is about $4.30 per gallon now, and the 91 octane for the car is about $4.60/gal.
So the Trail Boss gets 4.2 miles per dollar, and the Corvette gets 5.4 miles per dollar. Or about 30% more economical. And that is relatively constant, because the gas prices for 85/87/91 octane go up basically together. Here is a page that shows gas prices: