Not Worth the Effort!
Different topo maps vary on whether or not they show a trail winding up and over into Escondido Canyon. In fact, there is a trail, but you'd be one of the lucky ones if your map said otherwise.
Fortunately, it is highly doubtful that you could ever find the trailhead. It is unmarked and hardly noticeable. Additionally, it is very difficult to get to... those are all good things. A day planned for hiking on this trail would best be spent using that first hour of the day looking and never locating the trail's beginning... then, instead, you head over and hike Dog Canyon!
It is a shame. This trail has potential. The canyon portion of the trail winds around among some impressive high desert terrain, complimented with some really great rock formations, with those impressively touring cliffs and a variety of meadows and sotol forests. There is the feel of a world class trail environment as you wind your way higher and higher, and deeper into the canyon. It unfolds its vistas in stages, giving hints and glimpses of what is to come, then giving the full exposures in ever increasing doses... all pretty impressive. Unfortunately, to get up and into the canyon section you have to brave the initial mile of rocky, steep, slippery and rutted trail... a section that has not seen any maintenance in this century, and probably very little in the last one. And even once making it up around and into the canyon, the lack of trail work gifts you with a maze of spineys... head high, catclaw like shrubs that combined with the cacti and sotol and daggers, make for a total slice and dice festival. You'll be lucky if you notice the world class potentials. This section calls for full legging and long sleeve shirts... and not light nylon but better go for really heavy duty, armor level protection.
You will work your way up and through the worst of that, getting to a great meadow area that winds around and then up to another meadow and finally to an ever higher meadow, all the time drawing closer to the impressive cliffs of Gobbler Knob... but, it is somehow just not enough to justify all the effort. This hike needs a great end destination to make it all worthwhile. And, it is right there: Gobbler Knob! Unfortunately, just as shown on the map, the trail ends... Now, oddly enough, if you look further at the map you will notice that just up the north side drainage another trail heads on up to the top of the mountain... routing and connecting with the official Gobbler Knob trail... and that other section is not all that far from where this lower trail terminates. It seems logical to simply go for it... make the traverse and motor on up to the peak.
That is both a great idea and a very bad idea.
Those trails do not connect. It takes a certain dedication of mind and body to make that connection. Unless the lower trail section problems are resolved, it does not make sense to put in the additional effort, unless off trail bushwhacking is just something you love to do. Now, there is a potential that there may be a cliff clef traverse access straight up to the peak, but that has yet to be confirmed, and it would still need to have something of an access trail developed.... so, for now, just don't bother with this trail... It is not worth it!!
Note: in addition to the basic trail mileage you are likely looking at over 4 miles of cross desert hiking there and back. You should park at Oliver Lee State Park. There are jeep/ATV track routes that go to the trailhead yet it is not easy to drive them, and the security of the vehicle is going to be much nicer at the park.
Note: you will want to have a GPS route downloaded with you to attempt this hike. It is necessary for finding the trailhead and to give you a guide up and across the meadows.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.