I read the linked discussion and
1. Agree with not loading the towed vehicle backwards. Many have gotten away with it but it's definitely against the odds.
2. Many dollies are adjustable for the "track width" of the towed vehicle BUT BUT BUT some dollies are narrow enough in overall width that the track of a vehicle like a minivan may not fit, or the width of the towed vehicle may get into the fenders of the dolly.
3. And yes, get one with brakes.