If you have an adequate CE approved PFD that you prefer to wear, wear it and also keep a USCG compliant PFD on board. Stuff it in a hull compartment, bungee it to a crossarm, or sew additional pockets onto your trampoline - whatever it takes.
That's all well and good but, I know plenty of guys who spend large sums of money to save ounces on their boats, like buying titanium bolts to swap out for stainless,etc. .You are going to have a hard time convincing these people to carry an "extra"life jacket that's more dangerous than the one they're wearing for the sake of a greedy, bureaucratic, red tape wrapped law.
"I said, now, I said ,pay attention boy!"
The cure for anything is salt water - sweat, tears, or the sea Isak Dinesen If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most. E. B. White