I would have to agree, your type of fish don't really benefit from hiding in and around the live rock so it will not help lessoning stress of overcrowding. The puffer will be the big fish as you stated and they are very messy eaters. You will need some good mechanical filtration as well as biological.
50 gallon saltwater fish only...1 mated pair yellowtail damsels, neon dottyback, tomato clown, huma trigger, lemonpeel angel, 12 stripe wrase, bi-color blenny, dozen or so hermit crabs-scarlet and mexican, cerith snails, turbo snails, orange linkia starfish, 50 plus pounds of purple-pink coraline encrusted rock and a few mushrooms.
Redsea prism protein skimmer, 404 Fluval, UGF
with two 201 powerheads.
7 gallon tank with 6 pounds of live rock and countless brittlestars, 5 hermit crabs, snails and 1 False Percula Clown fish and Camel Back Dancing shrimp