In order to give a better sense of how the hardware will be attached to the bike frame, we created a quick sketch using a picture of our awesome bike and overlaying the envisioned design using a Wacom tablet.
And for the fellow Mechanical Engineers among us, here is a hand-drawn sketch of the zip tie gripping mechanism as well as the attachment between the electronics' case and the mounting brackets. Four keyholes allow a quick and easy removal of the electronics. The mounting brackets could be custom designed to fit any bike frame (tube diameter, horizontal/vertical mounting, ...) and 3D-printed on demand.
The left side of section B-B shows the mounting screws, while the right side reveals the way the zip ties are routed through the mounting bracket for optimal grip. Since my bicycle frame's tube is not round, the tapered edges also serve as a lock against any rotation along the tube's axis. Nice!