I've spoken with a landowner in the rural area of Saratoga, California, who owns a single parcel with more land than he knows what to do with, and I asked him why doesn't he build an MDU or some such, to which he replied that the city will never allow to re-zone and/or split the parcel of the land he owns, and that neighbours and such will generally be against any such arrangements, because it'll increase crime and drive the property values down.
However, what if said MDU had a restriction that only certain occupations could partake in it? Would it be possible to build a condo or an apartment complex, yet have some kind of restrictions such that you have to be an engineer or executive or some such, in order to either own or lease the condo / apartment? Or, perhaps, that each unit has to, (1), have at least a single occupant with an income much larger than what's normally considered adequate to service the rent, and, (2), no roommates from craigslist unrelated to the occupant? Could it be made that some such covenant has to survive all future sale/lease/rent of any unit?