I use a long slender backpack that I converted to a single strap cross body. it is deep enough to carry the scout and all the rest of my gear for the day and I can put it on my back when there isn't any action. when things start to get athletic, put the pack on with the pouch in front, unzip the top and draw it out and hand carry it. I do have a sling on mine to keep from having to constantly having to put it back into the pack. it makes for a really nice way to keep it close at hand in a tree stand also by using a carabiner on the carry handle of the pack it can hang down the side of your seat for easy draw. close the zipper for bad weather. kind of works like a large cross draw chest holster but with the bonus that it carries everything for your hunt.
I normally don't have anymore than 5-8 pounds in the pack as I don't like to carry anymore than I have too. day hunts locally don't demand a lot of gear like they might in the mountains or remote areas. YMMV