My donator status aside, I think this is an awesome idea and and even greater incentive to donate. Special maps can be hella fun. But I do see some loopholes with avoiding the 5-10 maps in between each special map. What if you swapped servers and tried the command there?
Maybe if they were integrated as a sort of special event. Maybe "!smart" could be used to start a special map which requires certain parameters in order to be possible. For example, it could only be activated at a certain time of day, or with a certain amount of players online, or even if it was to initiate a vote.
Not too sure, personally, just brainstorming.