For a stainless blade that is extremely tough (resistant to breaking) you can go for a very soft blade, a very thick blade, a laminated blade, or combinations of the above. I would suggest a laminated blade since that lets you have a hard edge and tough outer layers. The Fallkniven knives are good for this. You could look at an F1 or H1 with around that blade length.
A reasonable alternative for most of us is to get a medium carbon stainless alloy that is not hardened excessively. If you get a good blade profile it may be as tough as you need. If you pick a beefy design that is made from 420HC (say a Buck Vanguard), AUS-6, or Sandvic 12C27 you will get reasonable edge holding with some toughness.
For a bit less toughness, but more edge holding you might try S30V alloy. Take a look at the Alaskan Guide Series Buck Vanguard at Cabellas. (Do a search for Alaskan Vanguard) at the cabellas.com website.