I've been riding around on an Ancheer 250w hybrid for the last four years hauling an Aosom Elite weekly with a 30 / 40# load. NO grade problems here in NO, so no brake problems. Actually no problems at all with this combination. It's time to upgrade to a better bike and trailer as needs have grown a bit.
Carla Cargo trailer hahahahaha. As some one said in the comments there, with a little work you could have a chariot.