I have experience in rehabs and short sales but never in acquiring a property through buying a non-performing note directly from the lender and then foreclosing.  

They retain the right to call the mortgage based on the due on sale clause, but they have no incentive to do it since that would most likely convert it from a performing to a nonperforming loan and they don't want that.  

Even if you don't remove any contingencies on time the only recourse a seller has asked to send over a notice of buyer to perform which gives you another two days to handle whatever it is they're asking you to perform on.  

NPN 3 - Marketed as an NPN (correctly),  but is really a semi-performer.

I would like to invest a portion of my SDIRA in performing notes and have been reading about the process.

This is a simple task that all owners should become proficient at performing.

Buyer must represent "financial ability to perform" (if not contingent on sale of home, etc.).  

Toronto Groupon for $39: https://www.groupon.com/deals/gl-real-estate-wealth-expo-with-special-performance-by-pitbull

I purchase buildings all the time due to their being under performing assets. 

Better to overestimate and out perform than underestimate and hit a brick wall.