Any tips on installing floor-mounted-tub-filler?

[CountryBumkin]

I purchased a free-standing clawfoot tub that requires a floor mounted tub filler (at least for my application). I got the Pierre Mini-English (Whittington Collection from Signature Hardware) which requires 4 inches of the piping to be below floor for support.

My floor is a concrete slab. So I'm going to break open a hole (need to anyway for drain) and run PEX to location at sid eof tub. Instructions are for wood floor where access is from underside. Since I can't do it that way, my method is this:

I will connect PEX to to the bottom of stand pipes (by stand pipes I mean the brushed nickel pipes that go from floor to the water on/off knobs and filler spout) and back-fill with compacted sand. Then fill the hole in the slab around the new pipes with fresh concrete being sure that pipes are straight/plumb. Is this the best way? Do I need to wrap anything around the stand pipes where they are in contact with the cement?

[hj]

PEX would be the last way I would run those lines and depend on them keeping the pipes rigid. The company SHOULD have a bracket to support the pipes to the tub's overflow. If not Kohler has one that can be adapted by drilling and tapping an opening in the back of the overflow fitting. Other companies use set screws to anchor theirs, but without something to anchor it, you WILL damage the pipes eventually because of the leverage you can develop with those long pipes.

[CountryBumkin]

The tub overflow is at the center of the tub side and the fixtures will be at the head end of the tub, so I can't connect to the overflow for support. I suppose to could add a bracket/support at the base of the supports (under the slab). Since the tub is a 1 to 2 feet from the wall it would be difficult to attach any kind of support to wall (although it might be possible if I can find something). I could use copper piping under the slab for a couple of feet before I transition to PEX at the wall, if you think that adds addtional support.

So you don't think a couple of inches of concrete poured around the bottom 4 inches of the support/water pipes will be enough support?