The last option we have is to add $50K to the raise, which lowers returns, obviously, but not by a lot.

I originally was looking for the mythical 'structurally sound but killer deal because it has some broken windows and  hasn't been remodeled since the 1940s' type of place, but I've since lowered my standards to include properties with major foundation issues and the like.

@T.Yong Ling, you need to shop for a lower rate.

Some people strongly prefer to pay off their mortgage even though it doesn't make mathematical sense given that the loan rate (probably 2.75-5%) is much lower than what you should get in return on a good investment.

Typically, banks offer a higher interest rate to LLC than Individuals so you can see why this might cause a problem.If you move forward, then you would just update create an entry to put the value of building/land in asset and note payable in liability.

It will lower the loan amount and reduce the Mortgage payment.  

proper notice to enter is usually defined by the state as 24 hours notice. some states require 48. that is your starting point. that being said, coming through with a high amount of showings can be considered as disrupting the tenants right to peaceful enjoyment of their home. if you plan on coming through with one or two, you should be ok (legally) to give tenant prior written notice and come in regardless of their objections. if you think it may take multiple showings, you are likely better off to work with the tenant to set up a block of time for an open house. in extreme situations, you can consider offering a gift card to a local restaurant or movie theater to get them out. the tricky part is striking a balance between what is legal, entering with proper notice, and what is fair and reasonable, since the tenant can purposely leave the house an extreme mess to make it harder to re-rent, badmouth you to potential renters, and may even try to refuse entry. how you approach will depend on your relationship with tenant.

I've even thought about the idea of buying a lower value home and do a live-in flip.

I haven't pulled comps official comps yet, but just doing some self-assessment via Zillow with similarish homes sold in the last 6 months, this house already priced $25k lower than what those sold for (I say "similarish" because they were remodeled, had garages instead of being a duplex, etc.), which makes me think the sinkhole is NOT already fixed (this is a question I have out to my agent). 

Prices on the entry level homes have doubled and rents haven't followed fast enough.