Pennsylvania Gulch is a steep and technical alternative to the southern half of the Switzerland Trail
. Or, it can be used to make a loop with the southern half.
The upper section is mild dirt road (please observe side spurs that are posted no trespassing). The lower section, however, is steep, loose, and rocky OHV road. I can't recommend this trail in the uphill direction, but the downhill direction is a good exercise in keeping it together.
Halfway down, give your brake rotors a chance to cool off by checking out the abandoned mine ruins.