You could build a hell of a tank around a Mexican theme. Get one male and 3 female Swordtails or 3 male and 7 female platies (that'll be nearly as colorful as a malawi tank right there) then add a half dozen Juvi Firemouths and let them pair off. Get one or two pairs and take the rest back to the store.
Go with a pair of Rubber Lipped/Bulldog plecos.
The Firemouths should keep the livebearer fry to a minimum. Course you'll have Firemouth fry to deal with then...
Now, you may ask yourself, self, Why is he saying so many platies? I would answer that I read in TFH that they are best kept in larger groups, 10 or more to a tank.
If you went with the swordtails, you might (and someone else should check me on this) be able to go with 3 or 4 so Bosemani, Turquoise, or red Irian, or 6 or 8 Praecox or McCullochi Rainbows.
I'd try to hit neutral to slightly basic PH, with medium hardness to make everybody happy.
I'm a natural tank guy, and I still think that's a great layout you have there.