Back when I started my "Fish Only" tank that ended up being a aggressive reef, I really wanted a lion with my puffer. Well after much reading I decided not to do it because all that I have heard and read is that puffers will nip the fins on the slow moving lions. IF I were to do it over again I might try it but only if the lions were established first and I got a very young puffer that I kept well fed from the start.

As for the bare bottom FO...hmm I do not recommend that either for this main reason.

1. Substrate such as aragonite acts like a buffer for PH, without that you will need to dose buffers pretty heavily, or have a large refugium with sand in it but like you said you don't want to have to move it. Barebottom works well in some reefs because they have a low BIO load, in which a FO tank with Lions and Puffers will not have a low bio load.

I recommend doing a 2" deep special grade reef aragonite and just stirr it up every water change to keep it from becoming funky. I did this with my 100g and when I moved it all into my 240g it smelled like fresh seawater.