If you get any occilation without the trailer even at high speed there is somthing wrong either with the bikes mechanics, geometery, setup/fit, or the riders skills.
Any vehicle requires a totaly new and different set of skills the moment a trailer is attached.
I'm not saying it was your falt, any number of things could have gone wrong and without having witnessed it there really is no telling what whent wrong.
I do know of quite a few motorcycles that tow trailers as heavy as the motorcycle and rider combined.