My last house had the same type of room. I used gik traps in the front corners shaped to fit the slope ceiling, Michael Greene room tunes for 1st reflection points, and a gik super bass trap. I just built a custom home with a dedicated room above the garage but the slope starts at almost 8' on the side walls and the peak is at 12'. Same room treatments and the sound is much better I think because of the additional volume that the higher ceiling provides.
The last house also had more spongy/ springing floor and the tt could skip if walking hard. I put in much better floor joists and don't have that problem in my new house
The last house also had more spongy/ springing floor and the tt could skip if walking hard. I put in much better floor joists and don't have that problem in my new house