Quoting lil*Mama*Bearô:" <blockquote><b>Quoting Chim Richalds:</b>" Can you set up a particular space he can ... [snip!] ... What kind of mattress? We could totally try that. He got the idea from people knocking on the door. He likes knocking.."
If he likes knocking, you can get something else for him to knock on as well, tell him to knock on the tv stand or bookshelves maybe?
And she has a 6" memory foam mattress so it absorbs everything pretty much, lol. I can also basically fold it in half and make what she calls a "big chair" and she can jump against it that way too. It's sleepharmony brand, I love it