Bivyhunter. Its nice to hear somebody give advice that you can tell has actually been there and done that.
I've had some Kowa optics over the years, and had the opportunity to peek through many more. One more group of fanatics that swear by Kowa spotters is NRA Highpower shooters. The Prominar 88 is one of the few scopes out there that has the resolution needed to see 22 caliber bullet holes at 300 yards, in the black.
However, for a backpack spotter, and the one I use hunting. I LOVE my Nikon 13-30x ED50 with an angled body. For a true blue hunting spotter, especially for Muley country, its damn near impossible to top.
Another tip. For extended periods of glassing, get an eyepatch from Walgreens. Also, if you're going to pack a spotter and tripod, buy a bino adapter that fits your bino's (most brands, that plastic cap with the brand logo between the barrels unthreads to reveal where you screw in such an adapter) Both are things that can seriously cut down on eye fatigue. Mule deer is a glassing game