In a case like this, if there is a mortgage, bet your firstborn the lender will bid to get the tax lien (potentially up to the market value or the mortgage amount) to secure first lien position.

Have most of the passive investing/lending platforms gone south?

Your best bet is to try to find someone to work with/for in real estate to learn the ropes and make some money, put in a lot of hours and hustle, connect with as many investors as you can through local meet ups, and just keep grinding until you start seeing results. 

From what I've been learning, your best bet for a park of that size is to find an onsite manager. 

Told the guest the house had an issue and they'd need to call airbnb to be placed elsewhere (the online platforms offer this service for free as they should.

I would assume Fort Myers would be a good bet for you nearby. 

why bet against yourself and your own analysis?

As I stated above, I would bet 1K this supposed buyer walks if he has no success.

Welcome and Bigger Pockets is an awesome platform.  

I'll bet there are all sorts of things still left to do with the first one!!!