In California a motorhome is a passenger vehicle and needs no special license unless it is over 40 to 45 feet. The 40+ to 45' mho's require a noncommercial class B driver license.
From the DMV website:
To obtain a Noncommercial Class B license, you must:
Have completed all the requirements for a Noncommercial Class B permit
To apply for a Noncommercial Class B permit, you must:
Visit a DMV office (make an Appointment(s) for faster service)
Complete a Driver License or Identification Card Application form (DL 44 or DL 44C).Driver License or Identification Card Application form (DL 44C). (An original DL 44C form must be submitted. Copies are not acceptable.)
Give a thumb print
Have your picture taken
Verify your birth date and legal presence (you may use your California driver license). If your current name no longer matches the name on your birth date/legal presence document, see “True Full Name” and “How to Change Your Name” for more information. Provide your true full name if your name no longer matches the name on your birth date legal presence document.
Pay the application fee for a 5–year license
Pass a vision exam
Submit a Health Questionnaire (DL 546) dated not more than two years prior to the date of your application
Pass the traffic laws and sign tests for the class of vehicle your currently have and also the Driver’s Examination for 45’Housecars test
Call a DMV CDL office and make an appointment for a driving test (Cannot be made for the same day) (Noncommercial Class B driving test appointments cannot be made online)
Bring the housecar with you
Perform a vehicle safety check. NOTE: If your vehicle is equipped with air brakes, you are not required to pass an air brake law test or perform an air brake system check.
Pass a skills test
Pass a driving test