You can get an old child trailer, and a bunch of stuff sacks,
or that backpack you were asking about
and you wont even have to be that fastidious about packing.
just toss them in and go..

I have a Burly, the CoOp used 2 20" front wheels..

You could substitute some Skyway Tufwheels and that would be even more bomb Proof.

I think Travoy uses a 12 1/2" wheel with cartridge bearings,
Bike Fridays suitcase trailer Kit does too.

generally I would not want to do a free fall descent towing a trailer ..

I've thought about building a pair of wheels with drum Brake Hubs on my Trailer ,
so It can be a drag brake, itself.