My Steamroller is a bit twitchy in the snow even with 40mm Nokian Hakkapeliitta 240's. My cyclo cross bike handles better, even with 32mm knobbies, and I think this may be because the cross bike has a much longer wheelbase (partly because it's a bigger frame). So I'm considering using Surly Monkey Nuts to extend the drop outs to get the rear wheel further back.

Anyone tried something like this?

OK, either no one has any idea what I'm talking about or this is such a ridiculous question that it will not be dignified with an answer. Or maybe I should have posted this in the Winter Cycling forum.

BTW: the Monkey Nuts are described here:

https://www.surlybikes.com/spew12.html

I've emailed Surly to ask them.

Monkey Nuts are for pushing the axle back but still keeping it stationary when you're using a geared setup on the KM. This keeps the rear wheel out of the front derailleur when using fatter tires. You are running a fixed Steamroller; just add a link or two to your chain and slide the wheel further back in the dropouts. FWIW, a half inch or so of wheelbase will barely be noticeable. Your Steamroller is twitchier than your cross bike because the 'roller has steeper angles and tighter geometry.

gear down.
that's all you can do for better handling
besides wider tires.

Bigger tires help, but how does gearing down help handling?

FKMTB07 is right, monkey nuts will do nothing more than just getting a longer chain and running your axel farther back in the drop outs would. But, having run my old Steamroller with the wheel in the farthest out and also the closest position, I would agree that it won't make much difference. So, try that. Also, bar width helps for mixed condition riding, make sure you're using ones at least as wide as your shoulders.

More balanced when spinning through crud than mashing. Look at any cycling discipline that requires great handling skills: trials, polo, flatland, artistic.... low gears rule.

Thanks guys. Surly got back to me concurring with what FKMTB07said above.
I'm getting great traction from my Nokians (already over-speced on the Steamroller at 40mm) so no tire issues here. I'll take what wheelbase lengthening I can get by adding a chain link or two. Maybe then I'll at least be able to fit fenders.

I'll also go with rudetay's suggestion and replace the bull horns with a much wider Origin8 Gary bar I have.

exactly. Wider bars, bigger tires, and lower gearing will get you way better handling than even an extra inch of wheelbase will.

Riding in the snow is no different than riding loose condition trails. Big tires at reduced pressure, wide handle bars with an upright stance and low gearing.

No choice but to buy yourself a new bike. I suggest a Long Haul Trucker built with an ENO hub. That ought to solve your wheelbase problems.