JR, put OP_RETURN in front of the data script. That can't take more than a few seconds to change, and a few minutes to communicate. You may even be able to use dust/empty outputs in this case (you should, but not sure if the client supports it yet).
I think you are assuming that we have code which directly sends MasterCoin transactions, which we do not. Sends are currently accomplished using standard unmodified bitcoin clients (bitcoin-qt, blockchain.info, etc)
Given how much money you've raised it'd be quite easy to pay someone to add support for OP_RETURN to those clients, among other things.