As a retired military spouse I do understand what you are saying, but please also take this as someone who has seen many military candidates living overseas come down the pike.
It does not matter that you are overseas, when he goes for the board, his packet will be with a nom from your source, in your case that will include at least a presidential. The highest WCS wins the appt, regardless of where that military member lives. You should realize that your child will be competing against a stateside candidate from the same MOC. Thus, DODDS or CONUS mean absolutely nothing, the WCS means everything, and the CFA is awarded points based on their physical abilities.
Good luck, and remember ABOVE ALL...AIM HIGH!