I've towed through the narrows and it can get pretty rough, especially when the lake was really low. We actually had an older jet ski get swamped and start to sink, though we saved it, it was useless the rest of the trip. Since the water levels are nice and high this year and the Castle Rock Cutoff is open, there is no need to go through the narrows especially if you are launching from Wahweap. It will save you a good 1:30 - 2 hours by avoiding the narrows.
We usually tow 2 ski boats behind the houseboat until we get to where we're going, then untie and take the boats to go and scout for a beach.