I know few people have Sling TV. But if you do, you should be able to watch this game live, regardless of where you live. Just do this.
Search for "NFL Football". It won't show you our game (unless you live in AZ), but it will give you next week's local Fox game for you. Select that and record New Episodes. It probably couldn't hurt to go with New Episodes and Reruns.
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That's it. Go to your DVR and check your Scheduled Recordings. The Cards/Chargers game should be there, like it is for me here.
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Once the game starts, go to the recording and start watching. You can fast forward to the end and you're watching live.
I'm assuming this should work for everybody. It's been working for me for the past 4 years. Basically all Fox and NFL Network games are auto-recorded for me each week. There's nothing special about my setup. I live in Florida. I have no VPN.