I've seen so many people try realestate and walk away with nothing as a result of not approaching models correctly.

No reason to walk away at this point.

I could do four walk-in closets in a day, easy, with the time while I'm waiting for the coats to dry occupied by all the other tasks around the place, even with having to wash down parts of walls and scrub the baseboards, and painting ceiling and trim both. 

When I did mine via incFile that came with a referral to Bank of America for business bank accounts, and BoA walked me through that setup, pretty painless.For tax deductible transactions the software has each deductible category so any given transaction it either automatically knows based on the vendor and/or description, or it will ask you to set a rule. 

I would exercise your inspection clause and walk away. 

Point out that they don't have to fix things, clean up or have a slew of strangers walking through their house.

This doesn’t mean they walk all over you and get their way in every request, its actually better they’re told “no” early on, in a respectful manner.T- take in the profits – If you’ve followed this method and haven’t deviated from it you should be turning a pretty hefty profit and being paid well for the extra work you put in.

You can have a professional contractor walk the property.

I suggest you study the process very carefully before committing money you can't afford to lose.If you haven't search and examined title before it's not something you just walk down to the courthouse, or get online, and start doing.Check with a local title company to confirm their requirements for issuing a policy post sale.

Some quick and obvious ones include: 1) not being able to find a good contractor2) even if I do, not being able to get him/her/them to walk the property during the diligence period to give me a thorough scope of work3) if I need to back out of the deal after seeing the inspection & SoW, that particular contractor not wanting to work with me again and then me having to start the contractor-finding process all over again4) not being in a good position to manage the contractor throughout the process, thereby leading to an over-time and over-budget (and potentially incomplete/subpar) rehab.I could go on but you get the picture.