Hello Scott,
I am happy to report that this feature (response template in essay questions) in now part of Moodle 2.5 that will be released in about a month.
If you want to test it you don't need to wait so long, go to http://qa.moodle.net, login as a teacher and create an essay question.
I hope this new feature will be useful to you and other teachers, it was quite interesting to develop and not so easy I was thinking at the begining.