I'll need to be able to do it by myself- my wife generally takes care of the inside while I do the outside stuff. Love my daughter dearly- but not yet ready to require her. :-)
I was thinking a rear lip that I put one end of the table into then lift the front/closest side to me and "close" the holder.
I was thinking of angle aluminum for the rear and then rope or bungee or something for the front. I'm not sure yet if I'd have to secure it from shifting in any direction.
Measuring one side:
Measuring the other: