We too have found the various administering agencies to be different in their responses to rent increase requests. 

You can really set the guidelines how you want per property as long as they are administered equally to all applicants of that property and they dont violate federal fair housing laws or any state statutes.  

This means they way Prince George's County (or Howard County) administers their program can be quite different than the City of Baltimore.

In July 1979 the City Council adopted a Rent Stabilization Ordinance for mobile home parks and apartments and created the Rental Rights and Referrals Program to administer the ordinance.

It includes but is not limited to monies derived from Social Security benefits, supplemental security income, unemployment benefits, other retirement programs, child support, the Aged, Blind or Disabled Cash Assistance Program, Refugee Cash Assistance, and any federal, state, local government, private, or nonprofit-administered benefit program."

The state doesn't have anything to do with it, though, really, as Section 8 is federally funded, and deals with the housing authorities to figure out payment standards and to administer the federal funds.You won't be able to get the tenant's portion of the rent owed - from the housing authority, though.  

I don't see any need for city staff to administer the inspections, it could well be an "on file" issue just like your business license. 

If you refuse to even consider working with the HA that administers S8 isn't that discriminating against the tenant who has that source of income?  

Here a late fee can be no more than an NSF / dishonoured payment fee levied by the landlord's financial institution ... which is ~$50.00 across the major banks.As Marcia and others have said, a flat fee is much easier to communicate to the tenants and simpler to administer.

This structure is referred to as a Reverse 1031 Exchange, which are more complicated and costly to administer.