Rather than bedding blankets, I used furniture moving blankets.
I bought my really heavy ones from a moving company in East Los Angeles. They’re 17 pounds—two gallons of milk.
https://forum.audacityteam.org/t/too-compressed-rejection/52825/22
I bought these later.
https://www.harborfreight.com/72-inch-x-80-inch-movers-blanket-66537.html
They’re not as heavy, but they do work OK for echoes and reverb in a live room, the exact problem you have.
There is one odd downside to the Audiobook Mastering Suite. It’s a gift from the angels as long as your studio or recorder doesn’t change. If your voice level goes up and down by accident or there’s something wrong with the computer, it will drive you nuts.
Remember the original complaint was you couldn’t meet RMS. Now you do.
I need to go back and read your posts.
Koz