Stingray
I hope your son has had a great time, and some happy tales for you when he returns.
I used to teach D of E to cadets, and still mix with D of E students every month. Almost all of them have very large and heavy packs, but once they are on their overnight camp site, they all seem to be pretty happy about life.
Yes their gear is massively heavy, but many of them will not use it much, so there is no point in buying lightweight gear.
I can fully empathise with your desire to be going with him.