I think it's a little disingenuous to portray the coalition forces as the primary aggressors, and Nap as the victim, as so many are attempting to do here. Nap was actively attempting full domination of the continent including forcing a disastrous economic system on the continent. There's certainly enough blame to go around, but there are only two ways the coalition forces can achieve peace: defeat Nap, or roll over and play the part of a fraternity pledge during hazing (every time Nap whacks them on the buttocks with a paddle, they say "thank you sir, may I have another?").
I think Nap has to go after Russia. Sooner or later there's going to be a showdown. Unfortunately for him, though, his only real hope of victory is for the Russians to come out and greet him. It's a reasonable expectation. That's what most countries do. Portugal set the stage by offering no resistance and running, but that's what they'd been doing for a while, so it's no small wonder that Nap ignored that warning sign. They used the scorched earth policy effectively after the first invasion, but again, who would expect a country with real military power (Russia) to burn it's own countryside instead of fighting? Nap doesn't have to follow the Russians so deep into their country, but what's the alternative? hang out in Poland waiting for the Russians to come out? You can lay siege to a city, but not a huge country. Not engaging the Russians becomes a psuedo loss, and sets the stage for diminishing prospects for Nap.
Ignoring the Russian issue means that now you have a powerful country openly defying Nap's claims to hegemony, allowing a port for entry of British goods (Nap needs to preserve the continental system to starve Britain and also to preserve the notion that he's in control of the continent) and sooner or later the eastern european natives will get restless. It's going to take longer, but sooner or later Nap's empire diminishes.
And for the earlier suggestion that Nap give Poland to Austria: Russia wants poland. They weren't going to give it up to a powerful France, so why would they give it up to a much weaker Austria?