I have had two structures built by American Carports. They have several outlets in calif. Our closest is in Colusa, Northern Calif. I live in he Sacramento area.
I would use them....
The installers put together my 30x30x 13. shop, insulated 16x 12 rollup and a 8x7... Took them 2 days!
Both the camper barn and shop was built to the 90mph wind.
If you are going to have sides I would have the panels installed vertical instead of horizontal!
Horizontal collects dirt etc and is not easy to clean. It might cost a bit more but that is what I recommend.
https://americancarportsinc.comJim