You have read Roger Clark's article ?
Do not mod your camera. Modern SLRs have enough sensitivity that you can recover the faint Halpha red nebulas in post processing.
Use a dark sky, most Halpha gets lost in light pollution. A filter can be helpful, but is a workaround.
Here my results from an UNmodded Canon 6D (original, not Mk2):
https://www.skysurfer.eu/skypics1.php
You can of course use dedicated astro cameras, but they require lots of hassle, as you have to provide power supply, storage, etc. all yourself. A lot of hassle.