We have been through 2 months of appraisals with 2 different appraisers both of which have refused to appraise our property because they claim that there is a lack of comparable properties in the area.

I think the best way is to emphasize how you're giving them a deal by not increasing it more than the CPI or also show how your expenses have increased over the year compared to the previous year.

I noticed the Est Mortgage on BP is always $100-$200 off compared to the MLS.

Her rent was $1175, now $1350, anything comparable now is $1500 if you can find anything.

(I've been using the same numbers, same interests, etc) Anyone else did that compare and noticed the gap?

Plug that into the numbers that you run to determine the cash on cash return.From a housing cost reduction perspective, compare the rental income to the cost of the mortgage, taxes, and other expenses to see the net cost of living there. 

What got my attention with this property is how it compares to other water front properties in this rural area.

Are there comparables to look at for AirBNB proeprties?

I have a great rehab estimation tool and get decent ballpark figures, but in the current market, a lot of the highly rated general contractors are fully booked and investors are last in the pecking order compared to retail customers or large developers.

You should compare what they offer to an endorsement from an insurance policy to see if they are equivilant.