I still hang in with the premise that this partnership between Kam and Bryer is a sort of marriage. A very deep commitment, not only to each other but committed to some vision, some bucket list of the mind, something that has elevated both of them into a third powerful entity, invincible, unaccountable and irredeemable, in their eyes. It has a life of it's own, this commitment, unless one of them is already dead, unknown to us. Dead by his own hand, or by the other.
It is difficult to pin down the primary motivation of this 'adventure'. The Killing of travelers? the travel itself? the thefts? the fires?.. Killing the two travelers first off was one hell of a mighty risk, and one of those things that cannot be imagined beforehand, unless it was Mr Dyck who was first, but there didn't seem to be much time between the killings, but there WAS a gap, no doubt, and a move to another location, which underlines the commitment to the vision they hold. They had time to appraise what they had done and they did, and decided it was a fine thing and continued on to the next event.
I believe the killing was the prime mover in getting them out of Port Alberni, as a motivation and as a vision of themselves as roaming , invisible killers, of no particular target in mind except ease of victimizing. That is, I don't think they were searching for a couple, or a single bloke or a bus load of tourists... it was purely a chance thing, a 'karma' thing.
As they probably see their own death. As a chance thing, a thing already settled.