You don't currently have studio monitors, but could you? I run a community clay studio that averages about 45 monthly renters and 40 adult students per month, with Friday night drop-ins, afterschool programming through the local school system, and other random programming scattered in. We probably average 150 different individuals accessing the studio any given month. Getting everyone to pull their own weight and clean up after themselves is one of a list of constant challenges the studio faces.
There have been lots of good suggestions so far in the thread about the specifics relating to this piece of equipment, that kind of clay, etc, but for my studio, the most important piece in keeping things clean, organized and functional is my team of Studio Assistants. Each of these individuals hosts the studio for a consistent, weekly 4 hour chunk of time when studio members come in to practice/produce. All studio access for renters and students is contained to open studio hours hosted by a Studio Assistant. There are about 30 open studio hours per week... some mornings, some afternoons, lots of weekend time and a couple of late night shifts. The Studio Assistant arrangement is a work trade. They give their time in exchange for a set of keys for 24 hour access (outside of classes), a a large shelf space, a discount on clay, and most importantly the learning opportunities.
For each shift I assign the Studio Assistant tasks such as loading/unloading kilns, mixing glazes, pugging clay and cleaning/organizational projects. In addition to this assigned work, there is a closing checklist that Studio Assistants complete to make sure the studio is always left in good shape. Ultimately Studio Assistants are responsible for leaving the studio clean. Often times Studio Assistants have to remind renters and students to clean up after themselves... a "you missed a spot" kind of thing. The Studio Assistants who are less comfortable with confrontation end up cleaning up after renters and students... and quickly become much more comfortable with confrontation.
Without the Studio Assistants our space would turn into a heap very quickly. I could cover the place in signs about studio procedures and expectations, but without someone monitoring the space the signs would be ignored... people like making messes, not cleaning them up.
Oh... and prior to working in the studio, members must sign a form that spells out what they can expect of the studio and what the studio can expect of them. That way, if someone does blow off their responsibilities we have a signed agreement form them stating they'll follow the rules.
Ultimately, if you can take on some studio monitors and limit the hours of studio access to times when the space is hosted by a monitor your studio will stay in much better shape.