Almost everything is set except the seller hasn't been able to provide signed estoppel letters.

Get a payoff letter now and pay it off when you close and catch up her 2 back payments.

The strategy of the letters would be to get the owner in conversation prior to them going to the courthouse steps and hopefully making a mutually beneficial deal that can keep them from being foreclosed. 

You can do yellow letter campaigns to parks you google up:  <state> mobile home park.  

Hi Juan A duplex two blocks from a duplex that I own and live at just sold as a fixer-upper for 105,000 but Ive seen some other one's going for 160,000 up to 200,000 that I think should be fixer-upper's.

Send her a letter to both the address you found and the vacant address.

Without a local job, NO, but if they can produce a job offer letter, YES.

I send out a letter thanking them for taking care of my property and making it their home.  

i just mailed out my first set of letters, now im just waiting for my phone to start ringing! 

It occurred to me that a couple of years ago I created a bathroom in a lake house we had and I had to put in a rear discharge toilet (sounds redundant) to avoid cutting into the slab by drilling a hole through a cinder block wall.