My wife has wanted a puffer fish since I started this hobby (and we were only dating). I was a reefer-guy, tho, and kept telling her they just don't mix. When I upgraded tanks, I used my old one as the sump. Put some LR in there, left the sandbed, and added a little flour. light. After staring at the thing empty for a spell, I broke down and bought a Blue spotted Toby so the Mrs's would have her puffer (FOWLR Sump, basically). He's been down there almost 3 years now. Over that time, I've placed more than a few frags for temporary holding, and never had a problem w/ him eating anything (though it was never for more than a day or two). One time, I placed a Leather Coral frag I was making down below, as I was 'done fragging' for the night, and figured I'd just attach it the following day. Got home from work, grabbed my superglue, and went to get the frag out of the sump. Damned thing attached... so it's been there ever since. Hardly growing due to the lack of bright light down there, but never been bothered much by the toby, and is still kicking 2 years later.
I've also made my sump the point of banishment for any hermit or snail caught in suspicious activity... And they're still there. No empty shells. Your experience may differ, and the fish you mention are much larger than a toby, but I would think you could prolly find a spare 'shroom or two in a friends reef tank, and give 'em a go to see how things fare.
- Mac