To clear up the 506(b) and 506(c) confusion: 506(b) can be used if you have pre-existing relationships with your investors.

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If your replacing your roof see if you can write-off that portion of the preexisting asset or home.  

I would talk to a local mortgage broker there and see how difficult it actually is to piece the deal together.If it were me I would go after pre-existing homes but doesn’t look like there is a huge supply of multi family out there.

When considering purchasing a property through land contract with an existing mortgage on it, shouldn't the seller disclose their monthly mortgage payments and the remaining mortgage balance to the buyer?

They don't need an easement just to maintain their line BUT if they are adding a tap/upgrading/making money on that line that WASN'T a pre-existing condition then an easement must be granted. 

Even the local PM's are advising clients and potential clients that pre-existing STR's will be grandfathered in.

Rule 506 (b) entails that you must have pre-existing relationships with a deal sponsor.

And you mentioned “preexisting substantive relationship” issues.

Well I can buy a preexisting TWO family for $200k in my market so it was relatively cost prohibitive.But, if you can build an 2 bd ADU for $200k and units in your area go for $350k and the cash flow from the additional unit gives you well above 20% above your debt service, it might be worth looking into further!