So I've decided to remove the 2 middle tubes, move the 4 topmost tubes up so that I have more area to apply force to the ceiling (using printed parts) instead of the 4 points at the top of the vertical tubes and change the Y axis from 42mm to 27mm pipe, saving almost 2kg of mass and almost halving the cost.

I'm also planning to use clamp 179 as a base for the part that holds up each tile for each SecSavr Slab (I'm still thinking of a name for each gantry/bay/core/etc).