After working through all of this, I think you should not guide the hunt. Your personal morality is way too much in the way here. The couple have quite literally resolved any moral issues that are of concern to you, but you apparently, cannot. It is not your place to define their morality, and in most respects, there are no legal inhibitions in Canada, upon which you may draw support.
This makes you incompatible with this tour as a guide, hence, you should pass. In part, it depends to what extent you can provide each member with "separate" accommodations, ie each has their own tent. A makeshift wall is a sham and doesn't cut it.
If the male and female are not a couple then the courtesy would be to provide separate tents. You and he could bunk, if space is an issue. They've apparently indicated that they are more "accommodating" to the needs of the excursion than you are, so if that's case, provide her her own accommodation at a minimum, and consider a tent for each.