Plumbing

Some weird ideas here, but stick with me.
Shower: The whole room is a shower. I guess if I had more class, I’d call it a walk-in. But anyways, 4′ X 8′ probably multiple showerheads. I’m thinking a couple regular heads, a massager / wand head & a rain head (I’ve already got most of that) To keep the pressure up, I might have to get creative, been thinking 3 or 4 - 55 gallon drums with a booster pump & some kind of auto fill mechanism…
Regular elongated toilet, Hoping to get a good deal on one of them bidet seats I’ve seen on ebay.
Hot Water: I’ve got a tankless water heater from an RV, but it’ll have to be rebuilt, it’s been in a box for 30+ years. It’s a Rabbit brand, not sure what the specs are. I’ll edit this when I find it. Supplemented with rooftop solar, probably coils in a box.
Hot Tub: Yeah, the shower is in the room off the bathroom, but that’s also where I plan to put the hot tub. Why? Because I think outside hot tubs are a stupid idea. Talk about a waste of energy. Inside, in its own insulated room, makes more sense. Plus the neighbors won’t have any unexpected full moon sightings…
Got the tub for free off Craig’s list. Heater is dead, which is OK, as it’s electric. Picked up a propane heater off Craig’s list for $35. A little prest-o change-o, & I’ll have a nice little tub. It’s about 6′6″ square.
I picked up a big (like 3′ X 5′)skylight off Craig’s list for free, it’s going over the hot tub, so I will still be able to enjoy the night sky. It’s single pane, but I think it’ll be pretty easy to add a flat panel to the inside, along with an insulating curtain, for when not in use.
Sewage: Definitely seperate the grey & black water. Black would dump into a sump tank with a “trash pump” which chops everything up, making it easier for a small septic system to deal with. While grey would be used for irrigation.