What about a secondary muffler that attaches to your current one, just for when you are near your storage?
This idea came up when we were discussing the same thing with my car. Love the open turbo sound, but didn't go over well at 7am.
We were talking about some kind of a manual valve that could choke off the sound, and then be turned to open up again when it was safe to do so.
I ended up taking it to Hot Rod Scotts who specialize in custom exhaust and they added on one of their flat packs.