Tub drain clearance requirements

I'm remodeling an up stairs bath. The proposed new location of the tub puts the drain right over a joist. What's the "accepted" minimum offset I should plan on to get the drain in and all hooked up? If I locate the tub drain center 1 inch over from the edge of the joist, would I have any problems hooking everything up? I'll have access from below as well. I'm planning on a 1.5 inch drain that would increase to 2 inches after the p-trap. Thanks.

If you are using a solvent weld tub drain, then you can use fittings to "miss" the floor joist.
Sometimes I use two 45 els on the vertical down from the overflow, and move the tee back. Cutting into the wall plate lets you do this.