Clean Up Crew

I am planning a 15-20 gallon reef tank project and am thinking of a clean up crew to go along with it. My last tank was a 29 gallon with a clean up crew of 2 snails, a couple hermit crabs and a cleaner shrimp. One night I noticed a snail hadnt moved in a few days and upon moving the snail it spewed into the tank and let out a terrible smell. Since then I have wanted to keep away from any critter that uses a shell and stick to crabs such as the Emerald Crab and other creatures without shells. I was wondering if it was possible to set up a clean up crew for a 15-20 gallon reef tank without hermit crabs or snails (or anything else that can remain dead for a long period of time without myself noticing).