We typically use this unit as a mid term rental and then in between time while we try and fill the vacancy, we list it on Airbnb.

A french drain typically costs around $25-$30 per linear foot.

If you're unable to find comps within a 3 year time frame, I'm interested to know what your other search parameters typically are ( sq. ft. range, bed/bath count/ etc. ) , and also the locations you are unable to source these comps. 

Could I be missing something, or is this typical for the market right now?

If you have zero vacancies, zero tenant damage, make sure utilities (especially heat) stay on every winter even if the tenant doesn’t pay.  

But you have to understand the seller is taking on a significant risk of having someone else run the property and not knowing if they will get the final payout.If you are getting typical rates, why would you not just buy the property outright with 20% down and obtain mortgage financing from a lender?

@Michael Izbotsky In community property states like California, assets acquired during marriage are typically owned equally by both spouses, which may complicate transferring jointly owned property into your sole-member LLC.

The if is the challenge as ground up ADUs typically cost more. 

Typically $2m+ homes don't cashflow due to high taxes, high insurance rates, and low rental demand. 

It is typical for them to be bad.