RunThrough did fab Womble and tennis medals for their wimbledon common half marathon series last year so don't think they would appreciate you doing same. Although no reason why not I suppose just doesn't seem right though.
A female cut tech shirt would be bloody marvellous
Are you saying he is overweight? At age 7 this is a much more serious problem then his running style. Be honest with yourself - a healthy diet? Really? Take control of his diet now while you still can and he will learn good eating habits for life.
When I turned 50 I found myself in a new age category (usually) with less competition (usually). I actually came first in my age category in a local race, unthinkable a few years ago. Take time to be proud of your achievements, for some of us the podium has already been packed away by the time we finish!