I will bet that what you think needs a CDL, doesn't. Unless you live in CA.
Here is what I think.
1) Trailer 10,000 pounds or less, truck can be 26,000 pounds or less for a total of 36,000 pounds -- no CDL. Same trailer, but truck 26,001 or more---- NEED CDL.
2) Trailer 10,001 pounds or more, total of truck + trailer (actual or tagged weight) has to be 26,000 or less for no CDL. Same trailer, but total of truck, trailer 26,001 or more --- NEED CDL.
The weights listed are actual weight or tag weight -- which ever is more. So if the actual weight of the trailer is 9900 and the actual weight of the truck is 10,000 but the tag weight is 18,000 trailer and 14,000 truck -- a CDL would still be needed.
Did you win your bet or lose?
OP's original post #1 he stated he was looking to get a trailer in the 17,000 to 18,000 pound (gross) range. The trailers with that capacity are (empty) in the 7-8,000 pound range for a capacity in the 10k area. Trucks that can pull 17-18k will have tagged rating of 10-14k. Take the minimums and that is still OVER 26k with a trailer over 10k --- that would need a CDL. At least here in WI.