Or, is this a job for juju instead?
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.
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.