In all honesty, California has nothing to do with it. I've ran into multiple situations almost EXACTLY what you described in multiple states. Many times, while traveling through Las Vegas, NEVADA, the I-15 lanes were severely narrowed down, in the middle of town, to accommodate the massive amount of traffic that's there almost 24/7. Talk about being close, you have 18 wheelers within inches or less of you, all the while at 60 or more mph.
We've encountered the almost same conditions on the I-15 in Salt Lake City UTAH. Very narrow conditions, no real provisions for rigs like ours in tight situations. In Reno Nevada, we were on 395 South, a new section of it and, IT ENDED without no notice what so ever. I brought the rig to an almost screeching stop just in time to make a full, right hand turn, to drive over those plastic upright poles, to make it to and off ramp THAT WASN'T MARKED.
While I definitely feel for your frustration, and, it's definitely not right that either CAL TRANS or, any other operation company working in the area, did not appropriately set up the area for ALL SIZED traffic, I really don't think that So CAL is the only place that this kind of thing happens.
All of us might have handled your situation different or, maybe even the same approach. If it were me, I'm pretty sure that if I knew that I did not have the clearance needed for me to get through, I'd have stopped right there and called information on the Highway Patrol or, any other law enforcement establishment and get them out there.
They'd most likely see the back up of cars that I would create by not moving forward with GARANTEED body damage to happen if I did. Then, if the CHP would have ORDERED you to proceed, you'd have orders from the State of Cal to specifically damage your rig. You'd have names, badge numbers and witnesses. I doubt you'd ever see or hear those orders. And, the CHP would definitely make CAL trans and any other state or private companies make amends to the off ramp, to accommodate wider, longer rigs.
Scott