If doing a SoG pot size should be the largest you can use while still keeping your plants per sqft where you like it.
When I did SoG as a production method I ran 48 plants per light in a 4x4 foot area. 7x7 grid minus one for where the tray fittings are. Double that in a 4x8 (I used fittings and pumps on both ends of the tray). I ran 6 inch white square pots with hydroton. Ideally one could have a cover for the tray, with support feet so it won't sag. Then cut holes for tiny net pots. Put a coco mat in the bottom of the tray. Not the roots can just go nuts under the cover but you can't move plants but I never did. Just put any slacker clones in the middle like a stadium arrangement or even better root extra clones and only grow the best.