I have in my notes that some friends of ours who at one time lived somewhere between Perris and Lake Elsinore used a place in Lake Elsinore for their routine maintenance on their Class A gas coach that was slightly shorter than yours. I seem to recall theirs was 34' or 35' (?)
It's called Advanced Auto Care and they are a state-authorized emission testing facility.
They have enough room to maneuver in their lot according to what I have written down in my log that I noted from what our friends told us. I have never been there or used them myself but I'll give you some images of the facility location and their website so you can get an idea and maybe you can call and ask them if a 40-foot coach can get in and out of their lot.
Advanced Auto Care - Authorized Smog & Emission Tester for All Cars & Trucks
"At Advanced Auto Care, not only are we fully authorized to handle all aspects of smog testing for cars, vans, trucks, and RVs, but we're also highly qualified to handle all smog-related repairs."
Google Street View of the location - you can pan in and out and move around to see the approach and departure entrance to the small mall they're in. They are at the back of that mall ...
go HERE
The screenshot of the satellite view shows what appears to be a Class A parked in the corner and perhaps the area I have designated with an arrow is where they do emissions testing? ...I don't know.