My guy is 6 in November- but smallish (45" tall and 35lbs or so).
We are working on getting him a pack to carry- but as Caleb mentioned- just a simple Spidey man kids pack was plenty. If you wanted to push- I'd stick with 20% of bodyweight total.
But as you mentioned- it might be worth a trip to REI to try on a few of the smaller womens packs/running/hydration models and see what happens.
We are working on keeping things compact and SUL for the kids in general- since parents will carry it anyway- that seems to be the best option.
That said-
kiddo bags.jpg
Here are two kiddo bags I made for my son and daughter. Basic bag made with a bit heavier shell (HyperD 1.0) for abuse, and Primaloft Gold insulation.
They both weigh 12 ounces finished and pack to a cantaloupe size.
His is a quilt style that is 56 tall by 42 wide, with a simple sewn footbox (18").
Hers is the same quilt but folded up into a sleeping bag with a half zip. Roughly 42" tall by 56" circumference and a 24" zipper on one side. (she's 2 and a squirmer so we wanted her "trapped".)
If you're on the ground- that is a Exped Hyperlight Duomat they are on- which is tight for two adults but just right for a kiddo and a parent to share, and at 27 ounces is about the same as going with a large neo-air for me and a small neo-air for my son. This combo works a bit better and unlike the Neo-air- my son can blow up the Exped himself with the schnozzle bag that comes with it.
If you made these with a SUL shell (Membrane 10) they would drop to the 9 ounce range and pack smaller- but figured might as well make them with a heavier beat up shell as the bags have become a fun toy around the house too.
At my son's age- he's just getting big enough to get in and out of a hammock safely. So I made him a parallelogram hammock that came in about 4 ounces and packs quite small.
Gotta play with the suspension a bit- but I could probably get him a dynaglide rig and keep the tree to tree total at well under 8 ounces. Likely an 8 ounce tarp to match it.
kiddo hammock PL.jpgkiddo hammock PL2.jpg
So that would put him at:
12 ounce bag
8 ounce hammock
8 ounce tarp
12 ounce backpack (probably a home-made job with an easy way to attach it to my pack when he inevitably gets sick of carrying it.)
Then he could rig his own shelter and carry it at roughly 40 oz of baseweight.
A jacket, small water bottle, whistle, flashlight, and some toys should put him in the 5-8lb range at which point I'd cut off anything else.
He's really excited at the prospect- and even learning to sew himself- so why not?
kiddo sewing.jpg
As fer the two year old....
She will sleep with me just fine in a hammock- but still prefers Momma.
Momma prefers a tent.
Fer that- a Big agnes 2 man mountain spur- the aforementioned exped pad, and riding along in an osprey pack seems to be the best solution from 2-6. (My son and I did a trip with this rig at 5 and it worked out well).
kiddo pack.jpg