I think this is essentially what I’m thinking of - a thin flush mount bracket:
A pair of those on each of the corners, maybe one in the middle too for 5 pairs, carefully located so they are a snug fit (maybe counter rotated 2 degrees), would hold well in all directions except 1 (the direction you insert from). You could drawbore a pin/bolt to keep the table in tension against the hardware.
Edit:
Yes I was thinking these would be countersunk so the pieces are in contact. The one in the middle I guess would resist bending of the wood for seasonal movement if it tried to lift up. Nothing is really holding it down.
And yea, your latch previously, or any other number of solutions would work in lieu of the pin. I think it’s important to be kept in tension or compression, a simple bolt from top to bottom I don’t think would be adequate. It needs to have spring pressure to preload the hardware.
I guess if the way they are flush mounted is done just right, maybe mounted at a downward angle so the brackets are really snug and get tighter as they are inserted, then a light tap would “seat” them in tension against the friction of the 2 surfaces in contact. Then a simple bolt would secure to make sure it doesn’t loosen.