OK, I shot it this evening. Rolls of Portra 160 arrived, and I ruined a roll trying to get it loaded: 828 is not merely a little thicker than the custom Compass rolls, it's a lot thicker. The backing paper is very thick on these rolls, and the caps on the spool were far too big in diameter to use the spool unadulterated. So I had to pull the caps off, try to roll out some of the film, and then load a half-sized roll. And it didn't work.
But it left me with a brass spool that basically fits, so I tried rolling from a 35mm cartridge in the changing bag, and that worked out. So I have a couple shots (that were more than garbage).