Seeking Advice on Drum Room Location

[skankhunt42]

Hi All! I wish I found this site months ago! It would have saved me many sleepless nights trying to figure out this hopefully obvious question I'm about to ask....eventually, it's way down there. But first some background;

I am a drummer and own a 2bd single family home in Long Beach CA.
We have a kid on the way, so I need to vacate my music and hobbies from the 2nd bedroom within a year.
I've been playing on an electric kit for 11 years now but it's time to dust off my acoustic kit and play real drums again.
Decided that a new 2nd floor over the garage, built as a ADU, would be best for me and for resale.
Just got the ADU plans approved by the city and am currently seeking a GC to build it out.
The ADU will be structurally supported by four steel columns, one at each corner on new concrete pads with underpinnings to the garages slab, and will not rely on the existing garage framing to carry any load.
Both floors are and will be 22' wide x 20' deep 10' high in the garage and 9' in the ADU.

I'm a pretty heavy hitter and I'm guessing i average in the 120-125dBA range. I love my 19" heavy crashes and 20" china, but since my focus is on playing fast tech death metal, I keep my snare very snappy and bass drum a little tighter than average, plus half filled with pillows and a 4" porthole. I'm sure AI claims that makes the low end a notch easier to deal with.

City noise ordinance for 7am-10pm is 50dBA. The wall in the ADU where my drums would be is 6' from my property line, 20' from the next door neighbor's back pool house, and about 45' from a couple other main houses around me. It's a quiet area with very low ambient noise.

And here's my dilemma;
Originally I was planning to build a ~12'x9' fully decoupled sound isolation room in the corner of the ADU, using all the techniques, inner leaf of 2x 5/8 drywall + damping compound, staggered studs or isolation clips, 2-4" air gap, mineral wool, and then all that in reverse order for the outer leaf. Independent ceiling joist just on inner leaf, and a complex floating floor that has no chance of being installed correctly. And yadda yadda yadda, tons of other details for electric, HVAC, double doors with auto drop seals, etc.

I've been using Gemini (Google AI) to help figure out the best way to isolate 75dBA and that rabbit hole had me adding to the whole ADU itself with extra layer of 5/8 OSB on the outside wall, extra 3/4 OSB subfloor and ceiling with damping compound, mineral wool in all stud and joist cavities, baffle boxes for attic vents, asymmetric laminated glass with PVB interlayer with fiberglass frames, putty pads for all outlets and switches, and as heavy as a front door as I can safely mount. Best part is that all the extra weight from this and the music room means I need to upgrade the floor joists to LVL and reduce the spacing from 16" to at least 12" and go 1"+ on the subfloor thickness.

So even with all of that Gemini isn't confident that 1) something like this can all be 100% installed correctly and 2) even if it was, I'd likely only get 55dBA of isolation.

And finally my questions;

1) At a glance, with all the above, do I still risk annoying my neighbors during the day and zero chance I could play at 1am?
2) Do any of the smart people here live in southern CA? Can I hire you to design?
lastly, and this is why I'm here;
3) I'm guessing it makes more sense to give up my parking spot in my half the garage and just park in the street (which there is always tons of easy parking), and build a more affordable solution right on top of the concrete slab and not do anything I just wrote?
3a) Assuming 3=yes, then with an available space of 9w x 15d x 10h in the garage, does it seem reasonable to isolate 75dBA and still have 7x10x8 inner space inside the studio?

Sorry for the novel and thank you so much in advance to any help. I just want to do this right the first time and this has been a lot to wrap my brain around while also prepping for my first kid. It's been non stop anxiety for over a year now, so thank you again for allowing me to rant.