Been a while since I have been in the site so forgive the late response.
I have a BOB for my 6 year old. It has a water bottle, a 2.5 lbs child sleeping bag, pre-packed "outfits" some granola bars / energy bars, a coat, a whistle, a flashlight and a stuffed animal. The bag is a school backpack that has rollerblade wheels build into it so he can drag it if he gets tired. The whole thing weighs about 8 lbs. We live in Wyoming and go to the mountains frequently and he has not only carried it and enjoys the trips, but has learned (practiced) with it... ie "camping".
The one thing that I have to remember to do is update EVERYTHING! At his age he is growing like a weed and everything does not fit for very long.
Personally, it is the most fun I have had with my son. We are guarenteed to go "camping" at least 2 or 3 times a year. I get to teach him "stuff" like fishing, santiation ("Don't go to the bathroom in the creek son or too close to camp!"). He also learns the importance of being prepared just by the nature of having the experience. If we don't bring it - we can't use it.
My wife and I both have BOBs and update (and test) them by USING them. I also am a Nurse / EMT so I have a VERY extensive medical BOB that I have attached to a collapsable hand truck. It would be one of the things that I grab in my 3 minutes to get out (I want to beat the traffic). The hand truck can also be used for carring one or two of the BOBs should one of us get tired or injured (God forbid) and we have to continue to move.
We all have our mountain bike that I would try to load in that time just for back up transportation. I have a Jeep that makes Lora Crofts look like an amature. It is the vehicle of choice to bug out. If possible wife takes her SUV and I take my Jeep. She tailgates everyone so I am confident that she will stay close to me and not get separated enroute. If we do we have our vehicles set up with CB's (with sidebands), cell phones and GMFR radios.
Hopefully - we are prepared as possible, however, plans fail and situations change.
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A government big enough to give you everything you want,
is strong enough to take everything you have.
Thomas Jefferson