Also done both those drives, know exactly what you mean.
1. Chains are a huge pain the arse, plus not sure if ou can even fit them safely on 19", maybe 18.
2. Done the rent a car route, best part is your not as worried at the car but yes the bulk of the drive sucks.
3. If I have to take the M, I'd break down and get a second set of wheels and tires just geared for snow. Easy enough to swap out just before the trip. Downside, ride quality/performance will still suffer.
2008 E92 M3 Jerez Black,DCT,Fox Red ext,Prem,Tech,19", ipod/usb, CF roof and trim
2010 E91 328i Space Gray,Black int, M sport, most options
2007 Montego Blue 335i (retired)