Ok so my son is turning 3 next month and is a big guy (41 lbs). Wife and I want to be able to take him biking with us but I am starting to question weather or not a 2 wheeled trailer is a good choice. He has started to ride a bike with training wheels and loves it so I was thinking that the single wheel/tag along style trailer may be a better investment than a 2 wheel trailer. Thoughts on this? He is fairly advanced (sure all parents say that but our day care is saying it too so maybe he really is ) and clearly he is pretty big (only a couple of inches shorter than his 5 yr old cousin). How safe are the pedals/tag along style trailers?