I'd like some clarity on the California towing speed limit

Well, I have checked them having just received my class B. The weight regulations are only for trailers, nothing to do with motorhomes. They are governed by length. You can drive any motorhome 40 ft and less with a regular license even if it has the same weight as a larger unit and even with air brakes. Just doesn't make any sense to me. Some states have an over 26K lb endorsement requirement.