If seller is willing to finance 20%, is he willing to accept a subordinated lien or is he insisting on a first lien?

I would check with an appraiser and your municipal zoning officer to determine if they are acceptable.  

and then if they say no, do I wait a few weeks and then increase my offer by 5% until they accept?

One concern I have is if the lease is not in the sellers name, if lender will accept it.

Be upfront about the use of the building to make sure the AirBnB is acceptable.

The only issue is PMI companies don't accept this method so you need at least 20% down.

Hello,I submitted an offer on a 3b/2.5ba, 1990sq ft duplex style townhome (single unit, not both) in western Washington and my offer was accepted at $427k.

It generally covers issues like forgery, undisclosed heirs, and errors in public records.Lender Acceptance: Many lenders typically accept CLTA policies because they provide coverage for common title issues.

You follow the sheepsass in front of you doing the exact same thing as they do, or you ask them for advise and willing to FRIGGIN BLINDLY accept said advise COMPLETELY ignoring logic.For Pete's sake people. seriously.What do you want your seller to think?

Google requires a physical address for listing (even though he's field service) neither will accept a P.O. box.