Baby ring bearer...carried by a 15 year old?!?

Advice please! My wedding is coming up on May 9th. Our son will be 8 months old at that time and we really want him to be the ring bearer. We were considering my 8 year old brother pulling my son down the isle in a wagon, but my bro can be easily distracted, so that's a no go. I also have a 15 year old brother who is very good at carrying the baby, but we are wondering if he is too old to go down the isle. I don't have any bridesmaids to carry him, there's just my maid of honor. No grandparents will be able to hold him also. What to do?