My Warlock went just over 2,000 feet on a J290. My kind of flight.
If you want to keep it low, drag is your friend, even more than weight. A high drag, but lightweight rocket can get off the pad fast enough to be stable, but when the motor burns out, drag brings it to a stop pretty fast. I have one foam rocket that pretty much coasts to a stop in 5 seconds, no matter how fast it gets going. I use an Eggtimer Quark for apogee deployment, motor eject backup drilled a little bit long, no dual deploy. I could see adding a chute release. Eggtimer now has their Apogee altimeter that all it does is apogee deployment, and I plan on using those in future foam builds.
For a J motor, under 1,000 feet, you might want something over 10” in diameter. Drag increases pretty quickly with increased diameter.
I’m interested in what you come up with!