I know in Washington state, you can't rent out multiple slots to people with their own tiny homes unless you are classified as an RV park.  

The 83,000-square-foot casino houses 2,300 slots, 63 table games, and a high-limit room.

I have found in the case of searching for heirs (when the property has not been transferred after or during a Probate, etc. and you have a name only) their results for phone numbers are no better than the basic sites mentioned above.Lexus/Nexus or Westlaw (Reuters) can provide the same information with a lot less hassle although somewhat more expensive than LTO. 

Nexus comes in many forms, including physical presence, attribution, amount of money made, etc.Find out specifically what the filing threshold is for your type of operation, individual, business, corporation, etc.

The old meter slot is covered and this now becomes the sub-panel servicing all the circuits in the existing houseCan't stress enough the importance of planning for all utilities (electric, water, sewer & gas) from the get-go because these can very easily become showstoppers. 

Look at 2 to 4 unit building that you can use your mortgage slots for.. cash flow is better and your there to over see it.. nothing worse than being 3 states away and your having issues.

I tried to get approved for Lexus Nexus but no luck.  

Not really necessary but that would form the nexus between the two structures.

I've found nice pool tables there too, as well as video games and slot machines....

Your local title company can help you find your leaping off point, then sites like Lexi's Nexus can help you find phone numbers and possible relatives.If you have an agent you trust in your area you can ask them to join you on your hunt, they may have additional tools to track down any leads.Good luck!