I've been reviewing how I do staging in prep for going higher power, and I want to mention something you might want to consider with your personal risk tolerance. And emphasis on _personal_, I think these choices are pretty personal depending on risk tolerance.
I see you are planning to fly a single proton board. You might want to consider flying an eggtimer quantum + apogee or other small DD altimeter, instead of a single board. The reason is this: what feels like a "redundant" deployment setup (motor eject + electronic apogee deployment) is actually not, if the proton fails (e.g. bad battery connection), it won't light the sustainer _and_ it won't deploy the parachutes, so it'll come in ballistic. I had that happen to me recently with the TTV + Simple Timer kit, and that was really small and light, but the idea of something bigger coming in ballistic is too much for my risk tolerance.
If you fly two altimeters, one for sep+ignition, the other for parachutes, at least you'll have a properly redundant setup (and size might work in the sled, or you can put the apogee in the nosecone.
If you feel ok keeping the single point of failure, I'd recommend flying the sustainer alone first. That way if it gets off the pad, it'll have redundant deployment mechanism and you'll get to test the electronics.