Such a system might even serve more than one purpose (from a parent's view.) With the right Scoutmaster, who could teach the Scout how to properly use a bivy sack, the parents might not have to buy - and the boy wouldn't have to carry - a tent. (Of course, he might need a tarp, if that's not part of the group gear, so you'd have to consider tarp plus bivy versus tent for both weight and price.) However, with a bivy, you have to consider when he'll be using it: being shut up in a bivy in August can get a bit warm and damp on a clear night. That can be managed - again, gotta have the right person to teach him.

I spent several years happily camping with a weatherproof bivy and a tarp because it was lighter, more versatile, and fit more spots than a two-person tents. Then the manufacturers realized that you could make a lightweight solo tent that weighed less (Hubba, in my case), and I haven't used a bivy sack since.

My guess is the patrol bag and bivy combo weighs 5-6 pounds? That would be competitive with a synthetic 40 degree bag and a mid-range tent, and certainly something to consider..