I prefer cross draw for getting in and out of the truck, average walking around... a hammer thong or flap is essential for retention in either case. (your hands will be full of rifle/shotgun anyway)
It's expensive to find a good solid hi ride strong side holster w/ a retention screw for a cowboy gun.
I got my 'hunting' holster made by Trailrider products, it's a solid 1873 'cavalry pattern' full flap holster worn cross draw with 18 loops for spare cartridges. (12 didn't seem like enough) its' a good, servicable rig I've used for maybe ten years.
Try looking through the cowboy and "Hunter" leather goods at your local Sportsman's Warehouse... they have a big selection and don't mind you looking it over closely. Prices aren't bad either.
I almost always carry crossdraw with a large revolver, it's just more comfortable that way.