Consider both county and city restrictions that may affect certain neighborhoods.

Right now there are no STR restrictions unless you are in an HOA. 

It's a great time to be in development, not necessarily AirBnB in CA due to the ever-increasing restrictions and fire hazard severity zones - but that's still something great to have experience with.

But are their laws that restrict when one is allowed to do a subject to deal? 

While I have not encountered this, and know there are very odd requirements placed on property owners looking to develop land, this feels a little off given there are other property owners on the road and life-safety access tends to be the top most requirement in all roadways.

To your point about rental restrictions, each building has different rules and restrictions that need to be researched to determine which properties would work for your goals.

Get a feel for the local government, are they growth focused or are they restricting construction?

This is extremely common in the Detroit market, but it seemed very odd to me initially also.You simply put an inspection period in your offer so you can walk it and decide if it's for you or not.In terms of rent rolls, etc. you may not be getting a response on this for the same reason.

Regarding moving a mobile home on the land, you'll have to check with your local zoning office to see what restrictions there are on the land (if any) when it comes to removing the older home and replacing it with a newer one. 

I use technicals to identify buy and sell signals, but at the end of the day, you want to put the odds in your favor.