Personally, I assign my deals to my end buyers when working with sellers to help them find buyers for their mobile homes. 

I better keep that $2,000 in my pocket or bank account. 

After 2008 there were tons of forclosures and walk-a-ways that went back to the banks etc, so it seems like a SWD might not be that uncommon? 

Sure the bank wants me to keep some money in the bank, but shouldn't my minimum standards be better than theirs?

Has anyone found lenders (preferably credit unions or small local banks) that do HELOCs on investment properties, or are okay with a tax return that shows income generated occasionally on a 2nd home?

A pretty spreadsheet doesn't matter because none of us know how accurate your numbers are, your level of experience, how many times you have seen it in person, and what other property anomalies exist.

You might want to check out Buildium (affordable) and then AppFolio (you have to find out if you qualify with 60 units, I think min might be 100 units though).You will need multiple bank accounts.

To what extent you tell them how you structured the deal, bought the property or anything personal for that matter is up to you.  

My question is how long do you personally wait to see how your Airbnb venture is going to go until strongly contemplating long term?

I personally would start with family members and ask if they would sign a promissory note with simple interest so that you can take that loan and invest in buy/holds.