The Marron Valley gate mentioned by Adam Helman is still closed, I believe. But if you look on Google Earth the route of the main road is clearly obvious (grayish gravel color as opposed to brownish dirt.) That way (ie Marron Valley Road which does NOT dead end but transitions into the Otay Truck Trail), which heads a bit farther south from the gate and then comes back up to meet the closed spur, is perhaps a few miles longer but is not that much more of an effort in my opinion. It worked for 2wd and that's all that mattered to me!
I drove up the Minnewawa Road way (the road up the north side of Otay) on July 11. At the RV park, find a narrow, paved road at the west end of the entrance area. You'll know this road by the overgrown gate at its start. This gate looks like it's always open. It makes for a narrow squeeze between bushes. After that, no more bushes but the initial road is bumpy and potholed. It improves the higher you go.
Doghouse Junction is reached in a few miles. It is the most direct way if coming from San Diego.
As for the road up from the east off of Marron County Road, the following note is found in the Getting There section:
"Note A: I am not sure where this 'better' road begins. We did follow Marron Valley Road a bit south to where it dead ends near a firing range."
The better road starts beyond the firing range. This is evident from a review of the map and satellite imagery.
I passed several Border Patrol vehicles but they didn't accost me. All you have to do is look around you and you'll probably see one somewhere.
The final road to the summit can be driven rather readily (some brush encroachment to worry about but it's paved).