I like the idea of using bubbler nozzles on a pop-up head for this project. Consider digging some wells around the trees to assure that they retain water. I personally don't like the Rain Bird 1400 series bubblers and I hate the fact they require a pa-80 adapter to work with a spray head. And after that they stick up.
I much prefer the Hunter bubbler nozzles because they retract into the spray head body like a normal nozzle does. It also protects it and keeps it clean. They are also pressure compensating and come in multiple GPM's
If I was doing this I would do two or three .25 or .5 GPM nozzles per tree and set it up as flood irrigation.