Thank you for your comments, and welcome to the Nikon speedlight rancher's association. In no time at all, you will have your own herd of speedlights.
The sensors in the CLS compatible Nikon speedlights are quite sensitive. With careful line of sight alignment with the on-camera master, they will perform admirably.
Should you ever need to place remote units beyond the angle specified in the manual, when shooting with a wide angle lens, turn the head of your on-camera master unit vertical, and place the white diffuser dome on it. I have triggered speedlights that were actually behind the camera in this manner.
HBB in Phoenix, Arizona Nikonian Team Member
Photography is a journey with no conceivable destination.