Our idea is to continue living in our unit and have our next-door neighbor (attached unit) pay us rent, which would help cover our new mortgage.

I am actually sitting in the airport going to close on 2 doors in an area where they are. 

I installed a 2 1/2 ton straight AC with heat strip unit today for $3,900 out the door.  

So, changing locks, shutting off utilities, removing the front door entirely, etc etc.

The winter and summer temperatures wouldn't work letting a rabbit roam in the garage.

Still you’ll need to fix any plumbing, electrical, door etc type issues which likely are in bad shape.

Light went out, door come off a track, microwave/fridge lights burned out.

And I suspect there will be a ton of bidders when it starts that low.. wild to build a house like that with no garage. 

We currently own one door (split acquisition and closing costs and contribute equally to management and ownership), and have split equity and cash flows from the property - also pretty standard in my experience.My question is this - I want to purchase a house hack and would like to use our current business entity for accounting purposes (tracking income / expenses / etc).

Unless she expressly states she wants to know what you're going to do, or says you're responsible then I wouldn't engage.