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.