Regarding the truss rod. The way I think about it. Wood does change dimensionally with humidity (just a fact of life we live with). If you use a truss rod you have an opportunity to make minor adjustments to keep a neck in check with the tight tolerances we expect. If you add a material that is not subject to dimensional changes (or much less subject to), such as carbon fiber, steel, aluminum or what have you. You can control or limit that variance enough to keep things in check with those tight tolerances. You can work in some features (shaping your fretboard, build in relief, etc...) to give you more breathing room, but again if things go beyond tolerance your in trouble. I have had a graphite neck on a bass for years, no truss (although neck angle is adjusted with a set screw) and have never had issues. Mind you the neck is heavily reinforced and wrapped in carbon fiber around rock maple, composite FB. That neck still develops a slight bit of relief under tension, but it luckily is just right with the gauge strings I like. No truss requires a lot of thought, and design considerations. Ebony, although strong, is not going to remove the potential issues. So if you go without a truss, you are taking a path less traveled, it will be more difficult, and will have risks you will need to control.
If it were me, I would be inclined to resaw off a fretboard, add a tasteful lam if you need to develop additional thickness, and drop a nice double acting truss rod in that baby.
Peace,Rich
This is starting to sound like good advice.