Quick Update. I added the "kickstand" yesterday and wanted to share my pics. I hope someone sees this at some point and it inspires them to do something more elegant than this
. I used spare parts around the house so this cost me nothing, but the parts I'd guess would be about $15 new.
Gravity simply causes the leg, which is attached to a door hinge, to kick out when lifting, as long as the path is clear where it's crossing. I might add some guardrails later to make sure when stuff shifts around during transit that it won't interfere with the path when kicking out.
I wrapped the bottom of the wood in an old rag with zip ties to bind it, in hopes it would not snag my floor or any canvas or inflatable things that might go in there from time to time.
It's all attached to a nylon string with several screw in Eyelets to route the string around the top of the box. When it's time to retract the kickstand, I just pull on the sting (which is connected to the outer lip of the lid) and gently set the top back down.
Full view of stand deployed.