By the time you purchase a good battery, inverter, etc. and get it all installed, hoping it will work as planned you will have spent half of the price of this:
http://mayberrys.com/honda/generator/models/eu1000i.htm I just called them and the price is $669 with free shipping. I have the 2000watt model on my boat but the smaller 1000w will do you just fine.
It weighs less than 30lbs so your wife will have no problem picking it up. Mine starts easily and always, sips fuel and only asks for a 1/2qt oil change once a year. If your wifes workplace is secure, just place it on the ground in front of the car and only a short extension cord will be required. If needed a bike lock, chain, etc. can easily secure it to the car to keep it from walking away. She could fire it up at lunchtime or afternoon break and the car will be toasty.
The side benefit is if you do any boating, camping, etc. you will have the generator for that too. Should also run a gas or oil boiler when you lose power as well.
Lastly, these produce NO gas fumes when shut down. I, and many other boaters, keep these below when not in use which is a major no-no to any boating safety organization.
I'm a big fan, obviously as the engineering of these is simply genius.
RT