Here's the CA language on mudflaps:
http://www.dmv.ca.gov/pubs/vctop/d12/vc27600.htm
I am not a lawyer, but I read that as normal width tires or fender flares and enough rear overhang or mudflaps. It doesn't define how much overhang or any angles.
With an EB, I think I'm OK with just the overhang. However, I'm barely legit without fender flares with the 295 width tires.
On the Rock Tamers: A friend of mine who tows an airstream, which has (covered) windows right where rocks would hit has a set of them. They look a bit insane without a trailer hitched up, but they clearly work. They are physically big, so I can't see taking them on a trip and only putting them on where required.