I'm not concerned about selling a home with a properly remediated sinkhole along with the appropriate engineering sign-off, my question is, does anyone know of an engineering firm or company that can further investigate the sinkhole to determine exactly where and how large?

You can’t really know that unless you have done a thorough investigation of the property and know what to look for.

I screen my own tenants and pretend I am a private investigator trying to find where they are lying to me. 

Most common issue I see is people getting investigated for BAH fraud when they claim a different location to get higher BAH but they have no tangible property or a rental agreement.

I'd like to investigate putting both these properties under an LLC.

for the long-haul as their rates could shoot up, but worth investigating.

Here is the table of my journey:DayDateStart TimeEnd Time11/28/20215:55 PM6:15 PM21/29/202131/30/20218:00 AM8:15 AM41/31/20213:00 PM3:15 PM52/1/20216:15 PM6:30 PM62/2/20215:50 PM6:20 PMEmailed two loan officers asking if they could give me an idea on the interest rate I can get (heard nothing back)72/3/202182/4/20217:20 PM7:35 PM92/5/202110:20 PM10:35 PM102/6/20217:25 AM7:40 AM112/7/20219:20 PM9:35 PM122/8/20214:20 PM4:35 PM132/9/20217:20 PM7:35 PM142/10/20217:00 PM9:15 PMAttended the Feb StL Real Estate Investor Meetup152/11/202112:25 PM12:40 PMScheduled time with Peter MacKercher at StL Mogul and filled out his questionairre.162/12/2021172/13/20219:10 AM9:25 AM182/14/20216:20 PM6:35 PM192/15/20214:30 PM4:45 PMChatted w/ Peter MacKercher from StL Mogul Real Estate202/16/20214:30 PM4:45 PMReached out to Peter's loan officer and researched Tower Grove Neighborhoods Community Development group regarding their tenant screening process212/17/20217:30 PM7:45 PMFilled out my loan application222/18/20217:05 PM7:20 PMSigned off documents on new umbrella policy for primary home232/19/202112:30 PM12:45 PMProvided Chet more info on goals and investigated the docs he needs242/20/202111:10 AM11:25 AMReviewed pre-approval, reached out to Chet and team with questions and thanks, emailed Peter asking next step and some questions on other things to consider right now252/21/2021262/22/20217:00 PM7:15 PM272/23/20217:20 PM7:35 PMGot back to Tyson with Mogul (agent) and reached out to Eric Brand from Shelter Insurance, researched the type of lawyer I would need for writing a lease (Real Estate lawyer)282/24/20214:45 PM5:00 PMSpoke with Tyson about what I am looking for292/25/20218:15 PM8:30 PM302/26/2021312/27/20217:00 AM7:15 AM322/28/2021333/1/20214:25 PM4:40 PMSpoke with Eric Brand from Shelter Insurance343/2/20215:55 PM6:10 PMUpdated spreadsheet with insurance info from Eric Brand and reached out to Tyson on advice on making low offers353/3/20216:05 PM6:20 PM363/4/20216:55 PM7:10 PM373/5/20217:40 PM7:55 PM383/6/2021393/7/2021403/8/20216:30 PM6:45 PM413/9/20218:35 PM8:50 PM423/10/20217:00 PM8:00 PMAttended the Mar StL Real Estate Investor Meetup433/11/20217:30 PM7:45 PMSent Tyson a list of properties to try and walk through.

If a long term owner, investigate thoroughly, they could just be risk adverse. 

Travel cost to look at other propertyIf you travel, but you have not identified the property that you actually want to buy yet and the cost is considered investigating cost.

I would investigate Joshua tree with allowing more air bnb .