I have a Trailcruiser 30qbss which is a light weight 31' trailer with a single slide. Interior height is only 6'4" but because of it's lower height it greatly reduces the wind profile. Weight is not everything, but it is a huge factor. I weighed it at #5,500 loaded, dry weight is about #4,800. I would not want it to be heavier as it would make me want to have a more powerful tow vehicle.
Weight distrubution and sway control are a MUST as are trailer brakes.