I believe any boat trailer with 2 axles has to have brakes.Biggest issue is weight, not length of the trailer. The other thing you might want to consider is surge brakes on the trailer to help out. I'm not sure if someone has developed water-tight electrics...last I knew your only option was to use surge brakes.
You know whats funny tho, is there is a sticker on the SS trailer hitch that states the limitations. Not sure about the regular TB. Even though the book may give a higher value of weight, this seems to be the limiting factor.