Having visited the area and done some searching myself, including Smith Water Canyon and also this very ridge Adam Marsland investigated, my personal opinion is Nr 4. I went up this ridge thinking that it lies nicely on the 10.6 mile radius and could pick up a brief patch of Serin Drive coverage. The thing is, when you are actually there, the picnic area is right below you! You can't miss it. I can certainly believe that Bill might have reached the area, waited for someone to show up and been disappointed ( it being June and all ) - but I just find it hard to believe that he would then have wandered back into the wilderness, unless it was towards his car, and the Riding trail is a nice clear path to take towards that goal. Heat exhaustion definitely befuddles the mind, but it seems as if trudging up the dirt road would have seem more attractive: easier walking, the odd Joshua Tree overhanging it for a patch of shade to rest in ... maybe someone would come along!
Perhaps it will be worthwhile to walk the road and the area immediately paralleling it on the chance he did this and walked a few dozen feet off the road to rest in shade and never got up, but it seems like the searching already done in the location would have found him.
Back to Nr 4., the terrain in NE Smith Water is extremely ... craggy. There are so many places where a misstep can dump you into a crevice or where you could hole up for shade in a boulder pile and only be visible if someone actually crawls under the boulder. you chose My guess is still that this is what happened, and that every little cranny in that vicinity needs looking at. This would be a really time-consuming endeavor and require some high-resolution mapping of search paths and notes of what was looked at along the way - or else a lucky shot.
If I didn't have a pesky mortgage requiring my butt in a chair 40 hours a week, I would tackle such a mission. I have a bit of tolerance for repetitive, detail-oriented endeavors --- or I wouldn't have hobbies like poking around in the backcountry looking for needles in haystacks, or more precisely a few square inches of pigment or pecked lines in miles and miles of boulder fields ... or for that matter, gardening, patiently pulling weeds from between seedlings. Because my day job requires creativity and problem solving and many context shifts during the day I find such finely honed activities with almost mindless, singular concentration to be very invigorating.
Unfortunately, I'm a rare bird in terms of my attraction to the hopeless, the mundane, the repetitive. I can seldom convince my spouse to head out into the boulders with me.
