the only pocket that is safe to put a tracker in is the hip pocket of pants with suspenders and a bib, during a slide your jacket, pack, and inner layers can get torn off but statistically bib pants tend to stay on
i keep mine in the hip pocket of arc'teryx bibs but you should e-mail BCA and ask them for a harness, don't improvise with your tracker, you want that thing to stay on
remember when you're wearing it it should be only 1 layer away from the skin, so like a base layer and then tracker, not further in