We did actually consider making it a one way trip. We could have worked out the vehicle logistics but there were a couple other issues with it:
1. The one-way route was ~20km longer and much more portage heavy (41 on the one-way vs. 25 on the loop). When planning our route, we tried to make each day's trip shorter than one might normally travel (so that we had enough time for filming), and even then, I wish we would have made some of days even shorter than we had. That extra 20km would have killed us. In terms of portages, they were really something that slowed us down. With all the gear we were pulling, plus having to film, we were doubling or tripling () most portages.
2. The other thing we tried to do was plan a route than had something interesting / unique / special about it on each day (to try and reduce redundancy and make each episode worth watching). I was afraid that travelling the route down the west side of the park was going to be waaaaay too much of the same river travel - not too interesting to see several episodes in a row.
3. The loop was also more controllable. There were more detours / alternative routes for us to take if they were needed and we felt more confident that we could stay on schedule and make it down to Rain Lake when we needed to. We were worried about getting behind on the one-way or running into obstacles along the way.
Of course, all of this could have been remedied by making a longer trip out of it (i.e. more than 10 days) or re-configuring the episodes so that each episode did not necessarily represent one single day. But that was how the series was already laid out in the proposal and I had to stick to it.