The difference is mine were all in parks with no land.

If you try a tear down, you would have to rebuild it with parking, problem is the conservation district wouldnt let you build with parking. 

@Nick Adams @Andy XuGentlemen,I had toyed with the notion of going to multi family from the beginning but ended up the family modular home park business BUT I did have a lot of success finding contractors.

I have a SFH in San Carlos Park.

House #1 is a brick house in a quiet neighborhood in MD (next to a round-about), with 4 on street parking spaces, and room in the back, only grade is out front. 

If the current owner has awful tenants and a property in disarray, who knows if he has skimped on routine maintenance, leading to a lot of deferred maintenance (which you need to underwrite into your financial modeling).Keep this thread informed as to your progress!

I cannot interrupt a meeting with business executives for lack of toilet paper, someone's key card not working, or oh wait...where do I park?  

PS: Many, if not most, water systems will not take over individual metering on rented parcels such as an apartment building or trailer park.

The other two units seemed to be in serviceable condition.The parking area has old pavement that is not in good shape.

As long as it is a solid surface you would be able to park a vehicle or camper, trailer,  on the slab if you wanted to.That size slab wasn't cheep to put in, ugly it still has value.I'd just plain not think about it and leave it as is until you decide to change it over into a car port, shed, or put a fence around it.