A plunge pool gives you the best of both and allows you to maximise the space and your budget. Adding gas heating and spa jets and even a swim spa jet to a plunge pool would really complete this goal.

horizontal anything is a no, the gap would have to be so small it might as well be solid. yes the vertical cable might pass but you are not allowed to be able to squeeze them together as then the gap distance is non complying, The safest one is the solid section PCA pool fence, or glass, or solid, to 1200 mm in Queensland, no greater than 100 mm off ground, and gaps not able to be manipulated, and to stop that you have to have horizontal section in the cable type, which then do not comply, cut metal screens if complying is OK. I would question the void, and if you know the reason for the void, than solutions will be able to be worked out, now we are asking why? Pools in adjoining yards are acceptable with pool fencing complying on both sides, no void is required. so the void sound a bit iffy, unless it is something to do with storm water, or a building requirement, so ask the question why. Pool fencing can be awesome.

I'm not an expert, but we have renovated a pool and made 1 big mistake. We had similar coping that formed a big hob all the way around (unlike yours). We leveled it out with paving (and then coated the pebblecrete with an epoxy sandstone-look product). The mistake? Part of the yard sloped down to the pool. Every time it rained.....all the sand, dirt and debris from down the side of my house and around the pool went straight into the pool. If we had our time over- we'd leave a small hob around the side of the pool where the land sloped down. Yours looks like it is on the downside of your house with some garden. The hob might be there for a reason.....as we learned.

I would think depth is depth. You don't fill pools all the way to be level with ground. Even if hole is 3 metres deep surely the listed depth is how deep the water level will be