Take a look at this post on my blog – Central District Insider.  http://www.centraldistrictinsider.com/2019/03/17/paying-the-mortgage-in-advance-as-prepetition-exemption-planning/

The BAP’s opinion is here.  http://cdn.ca9.uscourts.gov/datastore/bap/2017/09/08/Ellison%20Memorandum%2016-1328.pdf