Spare tires were an option, but the Plus package on your trim level excludes them (due to the 20" rim size I believe).
Can you bolt on a donut spare and drive home in the event of a blow-out? Sure, but it's not recommended to drive very far or very fast, that's the main thing.
Also, it's not recommended to run the donut spare on a drive axle, but that's easier said than done, right? I mean, if you have a blow-out on the back, what are you supposed to do, pull a front tire/rim off and put back there and then put the donut spare on the front? I guess, but who is going to do that when you're stuck on the side of the highway with other cars whizzing past you at 55-75mph and only inches away?!?
Prior to last week, I would have advised you just stick with the factory-provided option for a flat tire and forget about acquiring a spare. That was my approach for both my Challengers over the last few years (I didn't have the factory foam thingy, but I carried a tire plug kit and 12v inflator to deal with any flats I might have while out driving, so basically the same as the factory approach). But then I finally encountered a situation (blow-out) which could not be remedied by plugging and airing up the flat tire, and I was stuck ~30 minutes away from home (where my donut spare was) with no way to even limp it there at low speeds.
After that, I have reversed my previous belief that a plug/patch kit was sufficient, and I now carry my donut spare with me 'just in case'. If you travel every day for work commutes and such, I would advise you do the same. You can get one of those donut spares from any local salvage yard for cheap. Hell, I gave my neighbor one last year when he bought an old Police Charger at an auction which didn't come with one. Those donuts are everywhere, and any late 2000's to current LX car's spare will work on yours (LX = Charger, Challenger, 300, Magnum, Avenger, etc.) that had one will work with yours, AFAIK.
If I am incorrect on that, hopefully someone will chime in with the correct info...