The last I know of BSP, was in 2000 at Essenden.
I think you are correct - it was being used to uplift live crayfish from Tasmania.
What was the registration of the other Trislander previously owned by Cape York Air and sold to Murchison Relines in Perth? I'm sure the registration was not in the BS_ series?
The two Cape York Air Trislanders came drom Douglas Airways who obviously acquired them from Bush Pilots.