Yes, changing the CS sprocket shouldn't take you more than 30 minutes. Loosen the rear wheel, slack the chain, remove the nut securing the CS sprocket, slide it off and reverse.
HOWEVER, why do this at the trailhead to save a few hundred RPM on your ride to the trail? You'll need to carry the extra sprocket (oily), probably won't have a torque wrench with you (bulky) and then there's the spending time wrenching instead of riding. In the dirt.
If you spend most of your time riding highway, then swap the CS sprocket back over before you head out in the comfort of your garage. If you go back and forth regularly, pick your compromise (higher RPMs on the highway or less low-speed ability on the trails with better fuel economy). I'm just saying...