[MagmaJct]

Looking at your pics, it seems to me your kill switch only prevents the starter from receiving power. Unless you think your starter is the source of your parasitic load, that's not going to work.

It looks like you have a yellow wire going from the battery positive to the junction block on the fender.

But I agree with what others have suggested. Perhaps your battery has an internal resistance that is causing it to self drain. A load test would likely rule that out.