There is a way to make the plywood work if you want. Keep the option alive for ya. You put the pre-cut plywood on top of the tile, not replace a tile. Then make your tile cutout with the plywood on top already. Sorry if that wasn't clear.
If you can take out one of the 2' Tees you can get the plywood 2x2s in easy. Move the surrounding tiles so the grid can flex a bit. There is a tab you push in with a flat screwdriver to let you take the 2' bar out. After, tweak the tab back and they will snap back in when you are done. The plywood will actually be closer to 23 3/4" or so. Just measure a tile.
Good idea to ask Axiom if the dog ear brackets will mount to 1" or greater material thickness. It's gonna be around 1" I'd guess when stacked up if you go 3/8" ply.
