Thank you for reaching out to me, I have since left the forum as I sold the car and couldn't deal with the boominess and the loud wind noise of the car. I went back to an ICE luxury suv. I will be looking at luxury SUV EV's in the future. I miss a lot of things on the Y but if it's not enjoyable to drive, you seem to dread it.
As for the things you've done above except for the tubing which is a genius idea, I will tell you it will not work for the boominess. It will work to reduce road noise, especially on the highway. I've put DOUBLE butyl on the wheel wells inside AND outside. On top of the butyl I put closed cell foam. All of this can be bought from Amazon under the brand Noico.
If I were to get a new Y I probably would do this all over again just for a quieter car. The solid stops helped the boominess somewhat but was still there. One thing this car needs is active noise cancellation, which it doesn't have. I read a post on this site that a new model S owner sold or thought about selling the brand new S because of the crazy road noise.
Don't put too much butyl on the trunk hatch as the strut is really weak, if you put your fingers on it with slight pressure while opening, it will stop.
Stupid forums won't allow to edit. I meant the tubing idea is genius and I've done all the things you've done above except the tubing. Except for the tubing as I didn't try it, the above things you did won't help with the boominess is what I meant.
So the weak point that I noticed is the trunk, it's on two hinges and if you shake the trunk left to right, it's not that secure. Going over bumps will cause transmission of pressure and noise through the roof/glass. There is one thing you can try that I never got around to is putting large washers under the bolts where the trunk lid bolts to. Remove/pull down on the top trim piece and there is two nuts on each trunk arm mount. I thought putting a flat aluminum bar or washers to reinforce it a bit, it may cause less flex/pressure. Again, I never got around to it. I even went as far as putting butyl strips on the seams of the glass wherever I could fit it.