I would weigh those two options out and see what costs less overall between an entire new loan and or the blended rate of the two.

Let's put expenses at 15% since it's a new build, and you're looking at a 10.2 cap rate.

Nobody knows what is going to happen with rates...trying to guess or forecast is a fool's errand. 

That way you can use that 2% to do a rate buy down to ensure a better cash flow.If you are buying it as a Primary owner occupancy I would ask for 3-4% seller credit to cover rate buy down and a portion of closing costs.

So I’m wondering if anyone has experience with other property investment friendly insurance companies with good rates before I start shopping around. 

That flips as you add units, anything 5+ for example the market for buyers is near 100% pure investor - so value will be mostly determined by rental potential (cap rate)

Too often STR owners are looking at extremely high occupancy rates like nothing will ever change.

Hello,I live in a pretty hot market, with very low vacancy rates and high property demand. 

With current rents and purchase price, it has a cap rate of 8%.

My goal: create an interest-free loan which is appealing to a potential homebuyer, yet doesn't make too big of a discount on my end.For example: If I sold my $300,000 house with 20% down ($60,000) over 30 years, at 6.7% interest rate: $1548.67 principal and interest per month1548.67 x 12 x 30 = $557,521.20What I would do would offer a lower monthly payment and no usury, but it would effectively be like a prepayment penalty.Arbitrarily, let's say 20% off the monthly payment, or $309.73 less per month: $1238.94 monthly payment.House would be sold at $446,018.40, which is $111,502.8 less than the total paid with a normal mortgage, but $116,018 more than the market price.