true^ I hadn't thought of that at first but it is a pita to get loose shrooms to attach, so if you can take some substrate with it it will make it easier to mount elsewhere.
also, once you cut them you can put them in a calm tub of water with some rubble and see if they will attach quickly, then you can just move the rubble.
Out of the 3 loose mushrooms I have tried adding to the DT over time only 1 mounted where I want and didn't end up behind the rock work. They're alive back there, but who can see em.