That may be, didn't really spend any time looking for an alternate route.
Correct, if you are driving on the mountain from East to West, and take the fork by the towers south, it will take you down the hill to Donovan.
I have never been the north way, but the bit you can see appears to be similar to the rest of the road. I think it takes you down to the 1000 Trails Pio Pico campsite, or around that area. No idea about gates though.
There are a lot of little side spurs along the way, some are a little more difficult but still generally no problem for even a stock X.