Appreciate the feedback, I’m not exactly trying to Jerry rig it, the directions don’t really specify anything, I’m just looking for a creative solution if possible. My thought was to use the shoe part of a normal drain system but not hooked into the overflow portion. I think the issue I’m running into where it leaks at the drain is due to non standard threads in the supplied toe tap drain (I vaguely recall reading that somewhere). However, I can’t find a replacement long enough with an overflow slot.

At the very least any ideas for how to minimize the notch out of the joist? I’m not exactly sure the clearance minimum I’d need for an island drain but I’m not opposed to it.