The idea I got from this was that unplugged approaches work with beginners as well as with those having more language.
I also found it interesting as a potential approach with EFL beginners overseas, if only we could convince schools to give up their precious (badly written) student books & workbooks.
Where it is more difficult for you is not having a common L2 among your learners, making a co-teacher arrangement useless. Where it is simpler for you is being in an English-speaking country where students are exposed to the language outside of class.
It sounds to me that you are definitely on the right track with these students, offering them what they need and want. You've also got me thinking about how a similar approach might work here in Taiwan elementary schools. Are there more sample sheets that you have developed under the "English Trees" concept?
You don't mention many specific ways of eliciting language from students. I assume, though, you might have considered student art, gesture, facial expressions, acting out, bringing in photos or realia as other possibilities.
Please keep up the action research, as good ideas are always welcome.
Posted today at http://jasonrenshaw.typepad.com/jason_renshaws_web_log/2010/11/a-simple-approach-to-trees-in-the-beginners-section-of-the-orchard.html