You have to ask yourself two questions. One, do I want a ticket for speeding or impeding? and Two, how courteous am I as a driver of a motorhome?
In answer to the first one, California law says "No person shall drive a vehicle upon a highway at a speed greater than is reasonable or prudent having due regard for weather, visibility, the traffic on, and the surface and width of, the highway, and in no event at a speed which endangers the safety of persons or property." Note that is says NOTHING about POSTED speed limits. There are ONlY two absolutes in California. You may NEVER exceed 65MPH and All vehicles while TOWING may not exceed 55MPH. There are separate sections in the CVC dealing with those....Good luck, drive safely and be courteous to other drivers.....Dennis