Re read your post after thinking awhile. Thirty or so years ago we needed a larger kitchen table. Most are too narrow for our tastes. We like to put serving bowls etc into the middle area.

Well we were laying hardwood floors that day. So I took a piece of 3/4 plywood. Put 45 degree corners on it. Did all the perimeter in leftover hardwood flooring, Then filled in the middle with the same flooring. Driving screws up through the plywood base into the hardwood flooring.

Then band sawed two pieces of hardwood and contoured them etc. Used hardwood banisters rungs to make an inboard type of pedestal mount. This so the legs would not be obstructive. People could even sit at the corners if they desired.

It is still in daily use and there have been no issues with it other than a refinish is needed as the edge finish has worn off now in areas.

A small batch of hardwood flooring could be found for nothing perhaps as it is not usually good for anything otherwise. You could even use the modern stuff but the edges are pre chamfered and the wife could not clean them. If you got a batch of them though they could be run through a planer to get below the chamfer. I see a table for eight as no problem.

The hardwood may expand and contract a little on top of the stable plywood but you do not notice it or see it. Logically it is occurring.