I am unaware of an existing TableModel or TreeModel link or tool to use with CouchDB. Hopefully others can give some advice.
Based on your question, I would suggest a preliminary project to make a prototype, to gain knowledge about persisting TableModel and TreeModel in CouchDB. Nothing fancy! Perhaps spend a few hours or a day or weekend trying some ideas. Usually, once you are comfortable with the problem and some solutions, it is much more obvious what is the best option.
To store on CouchDB, serializing to JSON sounds smart. Usually, the simplest technique will give the best bang-for-buck. I also suggest the wiki about using CouchDB with Java. There are many free tools, and each tool balances the pros/cons differently.