I truly don't view this business as convincing a seller to do anything, its finding the square peg and putting it the square hole nice and easy. 

I must admit, I am struggling a little on this one.We already made an offer on the home and the counter was decent, still keeping us below initial asking price.The offer was with indication that we would be doing an independent home inspection, always a smart idea.At first visit to property, there was concern on the diagonal/zig zagging lines in the walls, the few gaping holes where the stairs meet the home – evidence that the staircases had at one point pulled away/separated from the home.This cracking is by no means just settling, my limited knowledge of home construction was telling me, this here was a structural issue.But wait….. there’s more!

This would mean digging a hole in the right place and planting the existing mailbox at the correct position.

Also, screens, if present, must be free of any rips or holes.

I think you will see heat-pump driven dryers become more common as they are so much more energy efficient themselves and you do not have to cut a 12.6 sq inch hole through your building envelope for a vent (another inefficiency)We just replaced an{other} {only} five year old Maytag (made by Samsung) 24" laundry set (vented dryer) for which we could no longer obtain parts with a new Bosch pair this afternoon.  

ONCE your accept co-signers you set a loop hole for anyone else that want's to rent that doesn't qualify.. so you'll need to let others rent with co-signers.The only clause we had for using co-signer was if applicant was a student and then we would permit co-signers.She wouldn't qualify in my standards.

Could someone please poke some holes in my plan & thinking?

If you get someone that demands to see all the wiring and pipes they will demand holes get cut in the drywall for visual inspection. 

I mostly did it to escape the black hole of renting, and I'm now working on increasing my income so that I can start buying rentals.

With the credit card debt (and there is more to the story there I suspect - just having a $300 balance on a credit card does not cause bad credit) and car debt, she has dug herself a hole.