Now they have different leadership in government and the growth is exploding. 

Review title commitment and survey to make sure to deed restriction and/or HOA in place that would stop you from doing 4 plex2) Meet up with City/County planning office to make sure 4 plex can be build and lot has enough parking spot . 3) Talk to an architect to get an initial foot print, layout and foundation type (i.e. pier beam or post tension slab) 4) Bid out to get estimate for both soft cost (survey + construction drawings + Permit) and hard cost (cost of building)  Without #3 you really cant get hard estimate Problem is that you may not enough time to hash out #2-4.. prior to closing the land .. 

Any rent control from government or all free market?

The Federal Government can Trump the states.Marijuana is still a Schedule 1 drug (LSD, Cocaine, etc) for some reason.

@Derek Blades if you mean military housing on base that is owned by the government and managed by a contracted company.

Endless government regulations.

@Anand S. everything that was already said PLUS (something to keep in mind AND continue to watch as government policy changes) is the unskilled / semi-skilled labor supply.

The next thing you need to do is get blue prints made to what you want to do, get estimates. 

You are correct, if the home has been moved more than from the factory to the site or the dealers lot to the site, then all conventional and government financing is now not available for those properties. 

Knowing what a local government stance is regarding property ownership may limit what you have in mind or may not even allow it or they may place you on a time line that will not work for you. etc. etc.