Loftboy
I do get around
Easiest way to make a low alcohol version is to leave out the sugar when you are boiling all the ginger/spices up and then bottle/bulk prime as normal. Easier and less hassle than a ginger plant (no offence wildshwein)
The priming solution will give you approx 0.2-0.5% alcohol depending on how bubbly you make it. As long as your son isnt drinking 10L in a sitting you'll be fine
That way you only need to wait till it carbs up. As little as a week if you can sit them somewhere at 20 C.
Obviously it will still be a dry drink, nothing you can do about that unless you keg or like artificial sweeteners and i suspect most people here know my feelings on that topic
Cheers
DrSmurto