We are currently in a down trend that I expect to last three or more years.

Unfortunately, this is the primary reason I do not use third party vendors for rent payments, and I have posted on here a few times about this (usually when someone posts about a fraudulent clawback), despite the throng of enthusiasm for the continued use of these methods.Each one of my tenants is given a pre-designated bank account (idenitifed in the lease) to which they deposit rent. 

Do market research well to spot trends, demand, and chances to invest.

For example, MEP plans are not required for permitting, but if you are designing a complicated house, having a MEP plan certainly helps to guide the trades to know exactly how and where to install the fixtures, versus something they have to figure it out impromptu in the field.

Can anyone suggest a market where one-bedroom STR's that are nicely designed do well?

Security deposits are used for damages and are not designed to be applied to fees or rent. 

Our compromise was to design the upstairs to be like a private in-law suite so it could be rentable on Airbnb when we choose to do so.

Home appreciation has been still quite solid.Most of the rents went up barely, if not just trended flat.

S8 is designed to keep certain people financially dependent and financially illiterate.

Can anyone recommend a design build company that would handle any zoning needs with the city, as well as complete the construction and leave it rent-ready for me?