Well, from the horses mouth:
http://www.dot.ca.gov/hq/traffops/permits/faq.htm#9
I would point out that the Wide Load sign is supposed to be mounted at least 18 inches above the road, and if it's blowing in the wind, it doesn't meet the readability requirements.
"CVC Sec. 25104
Any vehicle or equipment that requires a permit issued pursuant to Article 6 (commencing with Section 35780) of Chapter 5 of Division 15 because it is wider than permitted under Chapter 2 (commencing with Section 35100) of Division 15 shall display a solid red or fluorescent orange flag or cloth not less than 12 inches square at the extreme left front and left rear of the vehicle or equipment, if the vehicle or equipment is being operated other than during darkness."
That does sound like the flags are supposed to go at the 4 corners of the truck/trailer, but it could be interpreted to mean that they go at the 4 corners of the section requiring the permit.
I don't have a way to attach flags to the front and rear of the truck/trailer, so I have just been flagging the front and rear of the machine, and the widest point of the machine if it's in the middle (paver, etc). With a load like yours, people driving past the flag on the back corner of the trailer are gonna forgot about it before they get to the blade!
One of these days I need to set up flagholders, but we are so slow right now I haven't had to haul anything wide for a while, and hopefully there will be a new trailer before I do again!
When I hauled our dozer, KW and Cozad? to Dunnigan for RB to sell a few months ago I had it set up like you do, except the front flags were on the front of the trailer instead of the truck because that's were the holders were.
The only thing I would do different is paint the blade corners, so that when Rufus is texting and drifts over and rips his roof off, there is no question of visibility! Otherwise move the flag lower. Mag mount flags are great for that.
I think Fl. Orange paint on the blade is more eye catching than a flag, and it has the look of solid steel instead of flapping cloth and says "Stay Away!"
Oh, and I would tie the Wide Load sign across the center of the blade. It would be more visible, easy to attach and I have never seen a rule saying it has to be at the exact rear of the trailer!
And remember that flagging only applies during daylight hours, darkness needs lights, assuming your permit allows 24/7.
I don't know where the guy got the idea of having 3 sets of flags on the carrier, and no mention of any on the wide part!
And if you still have unresolved questions after having several people that do this every day in CA comment on this (and I am not among that group, I just like reading the rules! ), you can call CHP Commercial Division and ask them how they enforce it, since that's really the only thing that matters!
Ben~