Or, is this a job for juju instead?
Per an answer to my original (since edited) question by bigjools, I'm posting his answer here as well. See below... thanks bigjools!
That's a job for Juju.
Another question - Is it possible to have juju use a MAAS server as the master node? - was marked as an exact duplicate of this, but it is not. I cannot undo that change, so I will answer here for now:
Right now, Juju randomly chooses a node from the pool of machines that MAAS manages. In 12.10 we plan to honour hardware constraints given when a machine is requested from MAAS. Juju should be able to take advantage of that, to target the bootstrap node (referred to as "master node" in the question) to a particular machine.
However, afaik, there aren't any plans to allow users to put the bootstrap node on the machine running MAAS.