I just received my 54x34 Swanstone pan. I am surprised at how lightweight it is. I cannot see how it could be installed without a mortar bed.
The grid ranges from approx 1/2" at the edge to o" at the center. It looks like a challenge to spread the mortar so that it evenly fills most pockets.

Second Question.
These photos are of the 8"x 16" hole in the slab for plumbing. Originally it was filled with dirt but it did not provide adequate support in the center. The old pan cracked near the drain.
Any recommendations on how to approach this? The Swanstone pan looks like it should have support as close to the center as possible.