If they are VERY professional, they will have their processes in writing as verification that it is enforced equally and fairly by their entire staff.6.

I would like to do fair by the owner, but my profit margin comes first!!!!

If you sell you will loose quite a bit in agent fees and you might never buy again in a prime location like Mountain View, You seem fairly young and have long investment horizon, if you are able to hold on to this long term you will most likely reap the benefits like its doing for @Maria D.   

@BOB CRANEY Here's a link to MD Fair Housing: https://mccr.maryland.gov/Pages/Housing-Discrimina...Familial status is a protected class, so even asking if the applicants are married could land you in a world of trouble.I think @Marc Winter's idea of "jointly and severally" language makes sense, but I'd check with a local attorney to be sure.

 There are many different ways to create a business model I would definitely make sure I understand all the laws and regulations such as fair housing discrimination fair credit reporting act and local property code before you go down this path you may be creating a lot of extra work in a lot of potential lawsuits and litigation if you’re not versed on the laws that protect tenants  I would just ask yourself what the goal of the reason you’re doing that is if it’s to save a little bit money or not deal with an incompetent property management company then you may want to change companies before you go through all of this work just as a side bar of what you’re trying to do

Real estate commission will be reduced due to my wife being a realtor.I am trying to figure out a fair deal for the owner of the lots whether it be a flat % return, a partnership split, or another type of agreement. 

As for physical property, if you live in or near an area that's reasonably affordable,has a good economy (for example if 80% of the town works for one employer you might want to stay away from there) and has fair laws pertaining to landlord/tenant issues I would look into actual property.

Is this a fair approximation?

I'm here too, but as a licensed agent we can't steer you to or from a particular neighborhood for fear of it being a fair housing violation. 

I have family in MKE and now a property so I'm back and forth fairly often, but probably not enough to hit one of their meetings.