Telescopic TV antennae work great for miniature omnis. They don't appear like microphones / recording gear to most people and their thin cross-section helps the black ones disappear visually when used FOB on a stand, but they would not be particulary inconspicuous on a table.
You could bend something suitable out of a wire clothes-hanger.
I won't argue that it's necessarily the best solution for your case, but sometimes lower is OK, or even better. As long as you have a clear line-of-sight from the mics to the sources, be that PA cabs, direct on-stage sources, or a combination of the two, height shouldn't matter as much at a seated table gig- certainly not as much as at a standing-room gig. If in the front row of tables, having the mics lower can actually help by increasiung the ratio of direct sound verses ambient room sound (more of the musicians, less of the room and crowd). Attaching the mics to the edge of a table can also be advantageous by eliminating the influence of reflected sound from table surface reaching mics elevated above it.