To each their own, but spending a day figuring out the bite on one river, then moving to a whole different river for the next day seems more like a sight-seeing trip than a fishing trip.
You'll get dialed in better, catch more fish, eat better/sleep better, and reduce the chaos factor by 96% if you pick one river and stay with it both days. Save the other river for another trip. With 8 guys you're gonna have at least 2 that get stone blind drunk, 1 that falls and gets injured, 2 that tempt hypothermia, 2 broken rods, and at least 1 that comes down with the Kung flu and is puking every 3 hours. Best to keep the trip more simple IMO.