final shower base install

[MarkHash]

I am finally replacing a temporary on-slab shower base in my lake garage project. I have the trap installed in the large block out area which is surrounded by 2x6's, sand and slab insulation. I have a Jacuzzi brand plastic shower base and want to set it in mortar to make it level, firm and quiet. My question is do I leave this block-out in the slab below generally open so the trap could be more accessible (dread that thought) or is it common practice to fill that area in with concrete patch or mortar too? Should I pry out the 2 x 6's too?

[Terry]

I leave the blockout open.
You need some room for the drain fitting anyway.

I also put on the p-trap last.
It's nearly impossible to set the trap in the exact location, and not expect the concrete to push it around during the pour.

[MarkHash]

Thanks T. As I recall nothing is glued yet underneath. You should see the 2 x 4, plywood and canvas shower base affair I have been using, along with the Teepee shower tent. Works but sure will be nice to have a real shower up here. I am using standard concrete block mortar, unless someone tells me different.