I wish I had come across your post sooner as our previous pool was very similar to yours and I have some advice.
Background on pool:
We were second owners of house and did not build the pool. Pool was built with the house as an integral part. House built on a steep hill with the hill grading down away from the front. Back part of house has “floating” concrete deck with solid concrete surrounding walls. Majority of house and all of pool and deck are all on concrete piers to bedrock. All built in 1996. Structurally everything extremely solid and very well engineered.
The problem with the pool was/is that, over time, the fill used around the shell settled. This wouldn’t be a problem since everything major was supported by concrete walls & piers except that the plumbing (especially for the returns) was supported by the fill. So with time, vibrations, and the lack of any activity on the soil to keep it compacted (it’s underneath a floating deck so nothing’s putting pressure on the fill) the plumbing began to sag. With more time and more sag, the plumbing would crack at connection to the wall returns (moreso around the hot tub, probably due to the jet plumbing having more horizontal run and more vibration from activating he bubble blower, etc). And then, to compound things further, once that fill gets wet from a leak, the fill starts shifting more.
So, my advice, is think about what’s going to happen with your plumbing 10 years down the road, how you’ll repair it (we were constantly having to jack-hammer the deck - thankfully with a “Cool Deck” finish it was easy to repair and blend the finish and color back in). If I were doing from scratch myself, I’d be looking for a way to support the plumbing from any means other than the fill.