For seven feet, you need 1-3/4" of drop.
Quite a bit for a 2x8
If you had even 1" of drop, it would help. I would stay with at least the 1.5"
And with the tub and the lav, it should be 2"
Is there room to drop below the joist an fir down the ceiling or box it below?
Sometimes you can tuck some of the run next to a wall.