Ptrap to Whirlpool drain

I am having some trouble deciding the proper order to install my tub. Today I have the tub surround framed out for a drop in whirlpool. The room below it is unfinished but is being sheet rocked over the next week. I will not have time to tile my tub surround prior to finishing the sheetrock on the ceiling below. So my concern is what is the best order for finishing this tub knowing I won't have access to the plumbing below in a few days.

Choice 1
1. Rough in Ptrap now
2. Use some type of slip nut to make the connecton from the tub drain pipe to the ptrap later
3. Sheetrock room below (happening anyway)
4. Tile tub surround later
5. Install tub after tub tile is complete

Choice 1 poses a challenge being able to reach the trap but I should be able to crawl under the tub deck framing. See pic below. Note - front access panel under deck wont work because of lighting below so the drain has to be on the back wall of house. I will have a side access panel from my toilet room. This choice concerns me because I am not sure if its a good idea to use some type of slip nut for the drain or if I am supposed to make a permanent connection.

Choice 2
1. Install Tub now (set in Mortar)
2. Use Glue from ptrap to tub drain pipe (permanent connection)
3. Tile later

Choice 2 creates an issue with not knowing the thickness of tile we may use (have not picked it out yet), so not sure how high to set the tub above the plywood deck).

My biggest concern of couse is not having a leaking drain.

What seems to be my best choice of action?

The easiest thing to do would be to leave out a piece of sheetrock on the ceiling below and finish it later. You could also have them finish the sheetrock but install an access panel below the tub for the plumbing.

I had thought of this however the space below is my new kitchen, so I hate to have an open patch in my kitchen for an extended period of time.

What I am trying to get is a feel for what type of connection should be made to the P-trap (glue vs slip nut), and whether its better to have the tile for the tub done before installing the tub. How do most folks finish thier tubs (install then tile, or tile then install) - and given my situation how should I?

The tub lip can touch, but should not be supporting the tub. So, to get the right height, it is generally easier to install the tub after the surface is tiled. For the best look, you want the tile underneath the lip, otherwise, cutting it to the edge and curves of the tub is harder to get to look good. You can use either slip or glued connections. Gluing gets you one chance to line things up. Easiest to leave out some drywall somewhere where you can still reach things. Unless the ceiling is going to be textured, doing it later isn't a big deal.