Funky Tub Drain Setup

[Fein]

I have a tub with an integral overflow in a second story bath. The drain for the tub is directly over a sistered joist. I REALLY don't want to move the tub or cut the joist so I set up the drain as shown.

I can't get the trap watertight (it is slightly misaligned so it doesn't seat properly)- so I will be taking this out anyway. I would appreciate any advice on a better setup moving forward.

Thanks.