Another option:
Lease swap. Let someone else take over the lease. It costs $500, which the new leaser can pay. Then you can wash your hands of it and get a CPO car and save some $.
Yet another option:
Lease a second car. I was actually in the exact same situation as you. Leased my M3, then my commute jumped to 80 miles a day. I would have paid close to $7k in mile overages as well. I shopped around for used cars but a $7k car is usually a POS. Do I really want to drive around half the time in a shit car? Personally, I'd rather pay $7 and drive around in my M3 all the time. BUT... then I thought about leasing an i3. It's not as nice, but I get to use the carpool lane, and I don't feel like I'm in a shitty used beater! PLUS BMW has 2 years free charging, so not only would I save on mileages on my M3 lease, but I won't be paying for gas! It was a no brainer. I found a great deal, and I mean really great. My total out of pocket is less than my mileage penalty. Insurance is an added expense, but I'm saving a good amount of money on gas. All in all, I'm spending about $50 a month net and I have the convenience of an extra car in the driveway.
Unfortunately you can't get any i3's now. You can, however, get some great deals on Chevy Bolts and Volts as well as Fiat 500e's for less than $200/mo. Check out a continually updated list here:
http://ev-vin.blogspot.com/2016/07/c...ected-evs.html
The Honda Clarity can be had for $900 down, $199 a month. That's a decent deal for a range of 366 miles.