If I am using milk jugs-----I place 6 of them in a large translucent plastic box.
When I use the plastic boxes for WS, I do not poke holes in them.
The covers are not a perfect seal so they are vented.
I use vermiculite in the boxes, and just add enough water to moisten it.
There is not need for drainage holes then.
Putting the little pots of seeds onto the lid and using the translucent bottom
is a good idea when the tops don't allow light through. (Wind might be problem?)
Your last idea to WS in the ground is also a good idea which works as long as the sowings are protected from critters etc.
