I am looking for something for wilderness survival that is rugged, powerful enough for white tail deer, and can easily be strapped to a backpack.
Have you considered the Savage? Not sure what model I'll have to find out but it's a single shot shotgun/rifle. The shotgun barrel was below the rifle barrel. I know it was available in a variety of combos. 12/223, 20/22mag, etc. IIRC, it broke down just like a single shot shotgun does which would be ideal for shoving in a pack or? Found it, here's the link.
http://www.savagearms.com/24f12.htm