I've only ridden in Arizona for about 35 years now so I may not know as much as others about riding in the heat. At times, I find it quite uncomfortable when stuck in traffic and the temperature is well in excess of 100 degrees. Maybe it's just me....
I also spend a lot of time on the Left Coast. Been there several hundred times over the years, both riding and driving. Usually riding. I'm sure I have thousands of miles splitting lanes and for the vast majority of those miles, have usually been given more than enough room to split lanes safely. I can say without reservation that in all but a few instances, the a$$holes that crowded me had OTHER THAN CALIFORNIA PLATES. Usually AZ or NV tags.
Please don't go on about special privileges. Unless, of course, you bring up the 1 ton extended cab, 8 foot bed dually with just the driver in it that takes up as much room as at least 4 motorcycles. Or the motorhome that takes up as much as 8. (Unless it's towing a huge trailer then it's up to about 12 motorcycles worth of road.) Or special parking for "Low Emitting, Fuel Efficient Vehicles" that motorcycles are prohibited from using. Or all of the Handicapped spots being used by people, and I use that term loosely, too daggum fat to walk to the store. Or bicycle lanes. Or pedestrians crossing the street with the "Don't Walk" sign flashing while they mess up traffic. I could go on and on, but I digress.
If you don't want to split lanes, don't. No one is forcing you to do so. Don't do anything that you don't feel safe doing. I know good and well that every time I ride my motorcycle may be my last. I accept that. If you're going to ride, you're gonna go down. Believe it. Motorcycling it self is not inherently dangerous. It is, however, extremely unforgiving of inattention, ignorance, and/or incompetence. Of the motorcyclist AND those around him. Riding at a snail's pace in traffic readily lends itself to inattention. I have never been anything but ON TOP OF MY GAME when splitting lanes. Or riding fast. That's just me.
All of that aside, I would much rather split lanes than ride on the shoulder.