It is not uncommon for people to hike the PCT with support at junction points, so the data is out there but you have to hunt a bit. I have friends who have done this. Also, there was someone a few years ago who wrote a book about this sort PCT hiking, but I cannot locate the info on that right now.
The best maps I know of, downloadable, free, and updated often, are HalfMile's maps on the PCTA.org website. Direct link to them:
https://www.pctmap.net/ Campgrounds are noted on these maps.
The
Pacific Crest Trail Association website has tons of info, especially under the "Discover the trail" section.
The book and film,
Wild, were crazy popular, but not very informative about the trail itself and the sort of data you need.
The PCT crosses a dirt road at Bird Spring Pass, roughly between the Jawbone off-road area and Lake Isabella; you can search for this on Google Maps. There is a crossing near the
Walker Pass BLM campground on HWY 178 near Lake Isabella. The PCT also crosses
Chimney Peak Back Country Bywayand there are some campgrounds along it. The PCT crosses Hwy 108 at the top of Sonora Pass, as well as all of the other trans-Sierra passes. I have personally been to all of these places with my Tiger RV. I'm not sure I would advise taking your much-larger Host Mammoth on either Chimney Peak Byway or Birdspring Pass road.
When snow is deep in the High Sierra or when parts of the trail are closed by fire damage, hikers often skip sections and come back to finish them later in the season.
I don't think that the PCT goes anywhere near Joshua Tree, but there was some talk of rerouting 15 years ago when I was active on this subject, so perhaps I should say that it didn't then but it might now.
Others will hopefully have more info to contribute. I'll follow this thread and answer anything I can.
2006 Tiger CX 4x4, 8.1 L gas V-8, Allison 6-speed