It sounds like you've given this more thought than many people who ask these sorts of questions, and have some at least semi-realistic thoughts on the expenses involved. It seems to me like it could work out okay. Real estate in California, at least near the cities, is crazy. You may have to get a used, relatively late model trailer and/or truck rather than a brand new one. Particularly for an RV, that can be an advantage as someone else will have taken care of getting fixed anything wrong from the factory.
I would think hard before getting a toy hauler for this plan, though. With a toy hauler, you're giving up half of your living room and dining room and kitchen space for a garage. It sounds like you'll be spending the majority of time in one place, or moving around areas where you'll have not a lot of time to use your toys. I would think that a "normal" trailer and maybe a small enclosed cargo trailer or shed to use for a garage would be much more comfortable. The drawback, of course, is that you can't take the motorcycles with you on a camping trip, at least not easily. (Many states do allow recreational double towing, so in those you could in theory tow a motorcycle trailer behind a fifth wheel if everything is properly equipped, but California is not one of those states. As I recall it basically works out that the East and West coast states do not permit recreational double towing and the interior ones mostly do.)