Laws here are being increasingly restrictive.

If you are comfortable with renting by the room, check the local municipality laws in the areas you are considering to make sure there are no restrictive laws about operating boarding houses.

On another note, you have some fairly restrictive laws regarding private lending, consumer protection (seller financing to an owner occupant) and loan servicing in CA state so make sure you are allowed to do this on your own and understand the licensure requirements to lend, broker loans, and service them as well.

In Texas, landlords can impose a maximum security deposit, which is normally equal to one month's rent.

@Aaron Laprade I like my area for this but you have to look at STR restrictions that a few of the towns are putting in place.

As for STRs definitely check the rules in your area cause MA has a lot of restrictions on days.

If the reason is particular to that lender, you can search for a lender that may not have the same restrictions. 

They are zoning and land use regulations, accessibility, environmental factors, market analysis, topography and terrain, utilities and services, neighbourhood characteristics, restrictions and opportunities, development feasibility, financial analysis etcetera.

Has anyone written this type of restrictions into their lease?

Pinellas County has one of the most restrictive STR rules in Florida.