What you are seeing being busted are trucks with no DOT registration numbers and whatever goes along with that. Or late model duallys and a trailer that pushes them over 26K total. If the dually is rated 13K, then you can't pull a 14K trailer without a CDL.
You DO NOT need a CDL to tow a 14K trailer as long as the combo weight is not over 26,000. And if the trailer is under 10K you can tow it with a truck that's up to 26K and still not need a CDL.
Take a look at the link below, you will see that the majority of states require a DOT number if the trailer and/or the truck are over 10K, even for intrastate use. Note that Indiana, Ohio and OK require the numbers.
This enforcement of this stuff is only going to get worse in the future.
My opinion is the best you can do towing commercial without a CDL is get yourself a trailer that's rated to keep you under the 26,000 limit. If you want to tow the most weight without a CDL the best combo might be a SRW 10K rated truck and a 16K trailer with two 8K axles and 17.5 tires.