You could start off with smaller numbers: 12 demasoni's and 4 yellow labs (1m/3f), and have them naturally increase their numbers (it shouldn't take long for spawning to occur if this initial group is comprised of mature specimens). There will be a grow out period before the fry become juvies that are no longer of edible size. You may want add the rusties at the same time (that is to say add all the labs, demasoni's and rusties at the same time...in a fishless cycled tank).
At some point in the future (perhaps when your demasoni and yellow lab population has plus'd up) you can add the zebras and labeotropheus. These latter species will have a more aggressive disposition than the rusties and labs. One male and several females for the zebra's and labeotropheus.
In my opinion, if you have and adequate number of females, male yellow labs and red zebra's aren't apt to cross-breed with the other's females. One the other hand other hobbyists may be of the opinion that red zebra's and yellow labs are prone to cross.
I've kept the two species together for over 5 years (4-6 red zebras, 7-9 yellow labs) and the only inter-species interaction between the two I've ever seen were:
- sub-adult male red zebra's (2.5"-3.5") occasionally challenging the dominant fully matured (4"-4.5") yellow lab males (with fully matured, my male red zebra's completely ignored the labs for the most part, except in the following instance...
- my matured male yellow labs would often engage in sparring for breeding rights and dominance among them. My dominant male red zebra rarely tolerates any fights that he's not participating in and would often break up yellow lab sparring bouts, while completely ignoring the female labs.
In regards to red zebra's being "peaceful" I'd say they'd live up to that trait AFTER they've firmly established dominance over all the other fish in the tank. If they haven't established themselves as the dominants they may be somewhat aggressive until that goal is attained. With your planned stocking plan I see only the labeotropheus possibly opposing them.