Are there any permits or regulations we should be aware of for rentals longer than 30 days in the SLT area?

From my experience, you should worry more for the management company & city regulations.  

If you choose to go this direction, make sure to find a company who specializes in parks and is familiar with all the state regulations.

They don't hold paint well over time because the internal moisture (the chemicals used in their treatment) wants to push out and will cause the paint to fail very quickly.Oil-based paint may not comply with regulations, considering how close you are to the water.

Regulators for example may tell a bank that they have to many investor mortgages. 

So for once instead of relying on the market to self regulate, Dodd Frank has ensured regulations to reduce the overall losses...Only thing that may come out of this would be that it opens up more inventory for distressed sales and more rental opportunities for investors.

I would check your by-laws community rules and regulations.

The goal here is to find out how much money you will need to put into the place (probably going to need to lump this into the "capital expense" category rather than deferred maintenance for a 20plex).Now check the regulating bodies.

I have received my license from the Department of Business and Professional Regulations (division of hotels and restaurants).

We're fine losing a month or so of rent to get rid of the worst case people before regulations cinch up too tightly.