You may or may not have problems keeping all your vegging on one table simply because when you have a small clone that is only 6" high, and a mother that is say 24" tall. What height would you have the light away from the tops? You may end up burning the top of the tall ones, because the light is too close, and your little ones will want to stretch to reach the light. Depending on the light you use, I would consider having them on different trays so the tops are more even to get the best use of your light.
I would also not put the hydroton between the plants, because you cannot move them or even turn them because of the rocks in the tray. Then to put a new plant into that situation can also be difficult.
I don't know why you are so against replanting to the appropriate size needed for whatever size they are. It saves space if you start off plants in a 4" net pot, and then once they are bigger and ready for flowering just transplant them. In fact if it was me, I would transplant them into a pot about 6"x"6" pot that is about 10" high. This gives the plant plenty of room for roots, and does not cost too much more in space. I would place them on the tray and instead of flooding the tray, I would run a 1/2" tube from your pond pump in the reservoir, bring the tube up to the tray where your pots are, and and leave a foot or two on the top tray with a plug at the end of that tube. Then run a 1/4" TUBE from the large tube, straight into each pot. You can just bury it about an inch or two into the hydroton. Then you can run the pond pump 24/7 and let her rip. There is so much aeration occurring that you will have no problem.... the nutes will run out of the bottom of the pot and drain back into your reservoir. You can get all the fittings from any Home Depot/Lowes in the irrigation department. Works like a charm.

sn