One form, ninety days, no waiting period, and a small pile of fees that shift depending on which side of the county line your ceremony sits. The offices are also not where most guides say they are.
Riverside County charges $111 for a public marriage license and $122 for a confidential one, and $96 for a civil ceremony at every location it runs except the 14th Street Chapel in downtown Riverside, which is $138. In San Bernardino County the public license is $120 and the confidential one is $135. A county ceremony there costs $100. The public license needs at least one witness present at the ceremony and permits a maximum of two signatures. The confidential license needs no witness at all and none signs it, but both parties must already be living together and swear to that on the license itself. For a sunrise ceremony in a canyon with nobody else there, the confidential license is the only lawful route. Riverside's schedule also prints $128 for a Saturday ceremony and states in the same line that Saturday ceremonies are not available at this time.
There is no county clerk branch in Palm Springs and none in Indio. Riverside County's single Coachella Valley office sits at 38-686 El Cerrito Rd in Palm Desert, open 8 a.m. to 4:30 p.m., issuing licenses and performing ceremonies for up to twenty guests. Appointments there are encouraged and not required. San Bernardino County works the other way around: marriage services are by appointment only, booked at (855) 732-2575, and the nearest full counter to the Morongo Basin is the High Desert Government Center in Hesperia, roughly eighty miles from Joshua Tree. The Joshua Tree office is an Assessor district office. Recorder-Clerk service reaches it on the second and fourth Wednesday of each month, and the county's own pages disagree about license issuance there, so call 909.387.8306 before you drive.
California imposes no waiting period and no blood test. A license may be used the same day it is issued and expires ninety days later under Family Code section 356. Both parties have to appear together in person with current government photo identification. A license from either county is valid for a ceremony anywhere in the state, which is the practical escape hatch for a Pioneertown or Joshua Tree wedding: buy it in Palm Desert, save the nine dollars and the drive to Hesperia. The one string attached is that whoever solemnizes the marriage must return the completed license within ten days to the county that issued it. Buy in Riverside County and it goes back to Riverside County, wherever you stood to say the words.