Hey stink, instead of draining all the buckets back to a common res, why not use the buckets as the res. In a system for large plants it puts you at a disadvantage having to raise them. I have an illustration of the common res method as opposed to the design I drew which is actually similar to some bucket hydro systems that you see in local shops, only they operate on a drip emitter rather than root sprayers.
The only thing I can see being a problem with this system is that it would be harder to drain and refill but thats really not that hard to deal with. Also, if your doing a bunch of big plants say outdoors in these buckets, you can step it up and design every bucket to have a garden hose attachment and then build as many as you like and connect both the sprayers and the drains via short garden hose pieces and then its super easy to clean and take apart whenever you need to, and if the plants become too crowded, just swap out the hoses for longer ones. What do you think!