i towed my blazer and a LOT of extra parts and tools on a 7k trailer. it had no brakes. my cummins had NO problems stopping it, but it has larger 4 wheel disk than most. not much engine braking with the 6 speed ether due to no exhaust brake at the time. i would advise asking if they can hop up the axles for the trailer in question. most of the trailer builders i have talked to built the 7k trailers just as strong as the 10k with the exception of the axles. maybe they can swap them out for a small cost. i woldnt advise going less than 10k, but 7k is doable. i did it, but i didnt like it. now i have a trailer capable of hauling 18k plus trailer weight. i wont go back to a smaller trailer ever. i know some people dont have the choice i had, and i know i worked my ass off to get what i have, to include selling my house( ok, not the reason i sold my house, but the reason i was able to buy the trailer is because i sold the house.)
10k 20 footer is the smallest i would go for a blazer. depending on your tire size if you are runnign smaller than 37's I personaly would get a dove tail on top of that.
just my .02 worth on it. in the end, get 2 braking axles no matter what you get. also the brakesmart is what i have for a controller and i have yet to use it personaly as my dad has installed it for me and he loves it with the 32 footer behind it.
Grant