I ended up making up a programming harness than linked the target board to my EPIC programmer. Similar to your schematic except I found I had to groundthe LV Prog pin of the PIC16LF877A TQFN package. Only a couple of fixable shorts soldering to the fine pitch wires and all 20 boards recovered in the end.

By enabling the WDT I was able to use the PBP SLEEP command and drop the idle current draw from 120 uA down to 8 uA (including two 32 Mbit serial flash memories).