Tom, I don't know if it''s still an option or what you are trying to get but CA had a "Non-commercial class A" when I was doing all my licensing crap. That was the one for trailers above 10k GVWR yet not used for commercial purposes. I'm not sure if the endorsements for doubles was available for that one though and you'd have to have it to pull both at the same time. The double/triple test is only on paper once you have a class A.
If all you want is a 10k trailer I'd check with friends who are into ranching. A rancher will almost always have a trailer rated that high or know where one is that you could grab for an hour or 3.
Have fun dragging both, it can make for an interesting day. When you get really good and impatient you can launch the boat all hooked up with the 5th wheel.