I'd say who cares in the light of a $50,000 down payment, do $100 really matter?  

Heck I will do most anything that comes down the pike if there is good money to be made. 

Seller finance deals work when one of the following situations is present1- property can’t be financed with institutional financing usually because property is vacant (commercial property) or in bad condition2- seller will only accept an above market price for the property and by offering seller financing opens the universe of potential buyers to include people who wouldn’t qualify for financing3- seller is able to obtain a “piece of the action” from a buyer rehabbing the property and hence ultimately obtain a higher price.4- the seller has an existing low interest rate mortgage and wants to “wrap” the existing mortgage into a seller financed higher rate mortgage and pocket the differential 5- property is an investment property, seller has a low basis in the property because of depreciation, and wants to spread out the taxes due.Are you thinking of trying to purchase with 100% seller financing, or are you able to /willing to offer a down payment of say 10-20% .  

.- There are more houses listed for sale and rent in the neighborhood, which is pushing rent values down.- My current lease is up in September and the tenant is leaving, and I expect my monthly cash flow to reduce to $950, lowering my ROE to 3.57% and ROI to 9.5%, again, without variable expenses.- Homes are staying on the rental market for a few weeks, sometimes months, even at lower prices.

Depending on your time period for construction, a heloc could be a great option as it provides flexibility and then you can always reuse later down the road.

The variance in your CAGR returns is because the $12k in the note is returned to you in increments throughout the life of the asset, amortizing down to $0 at the end of year 5.

In my experience the cash flow in the summer is strong enough to justify shutting a beach property down for the off-season.

Are you doing a turn down service at night, providing meals etc?

I'm also going to add some outdoor(deck) space and update the kitchen with new cabinets and countertops(modernize) as well as take out the carpet and put down lvp flooring.

This can include opening some walls here and there so the inspector can check if everything is built to code, then you repair or tear down depending on what they find.