Do the math and the answer will probably be obvious. 

I'm wondering about servicing these after completion on a longer term basis following a DSCR guideline as they will be rented, and then selling them in a secondary market.

The discipline to run on a budget for a number of years or decades depending on your math, doesn't factor in emergencies or market changes where the HELOC could be used to invest in other places.

Unfortunately - there are a couple of issues here that likely make this hard to finance:-"Cabin style" dwellings typically are difficult to finance as the secondary capital markets treats these differently than standard single family homes as the buyer pool for a "cabin" dwelling is less than that of a standard home.- Yurts: Lenders typically have difficulty financing Yurts as they are moveable collateral.

In the peak season the math is better.We started charging MTR a bit more for the four biggest holiday weekends of the year. 

dont over think this its not that complicated. important issues are.1. cost of capital2. knowing what a deal is or is not.3. good reno crew or contractor  4. good agent that will tell you straight what its worth when done and what level you should rehab to.5. a market that is actually moving napkin math works  trying to drill down to decimal points does not.

It seems like I need to check further away from the DMV area.My feelings are if you want “cash flow” you should buy a bond (I really like the tips rate right now) there is next to no reason to buy real estate for cash flow, if you are going to buy you should buy with appreciation in mind, which is not to say that’s the route I’d go, I’ve been liquidating properties to put in stocks and money market funds over the last few years and u just did the math and I’ve come out well ahead, but just to say there are arguments for stocks/bonds, there are arguments for levered appreciation, but the cap rates pretty much anywhere aren’t worth it vs an inflation protected bond, especially since a 3/rd of inflation is real estate anywhere, you could get “cash flow” and inflation protection much easier through a tips.

The math says to perform $500 sewer clearing each year instead of $5000 excavation, but the $5k bought peace of mind.

That's some funky math bro.

The math is obvious but there's a natural tendency to go for properties you can obtain at a lower basis.