Many small databases

I’m evaluating couchbase for a webapp where I plan to have many small databases.
It’s a management sw for very small business every customer should only see his data when querying the server and when syncing locally.
I want to be prepared to host a few hundred customers, each customer should need very few resources.
Currently I’m using couchdb and each server memory is shared by every database which is ok for me, but I’d like a strongly consistent cluster.
With couchbase I see that I have to assign ram to each bucket on it’s creation, so I’d probably be forced to put all customers in a single bucket am I right?
How can I make each customer only sync his own data?
I’m planning to start with the community version.