Good idea. I will probably tried it. Mostly turned off for my flatscreen TV except CFB games.
BTW, only $20? No up front?
Sling TV is $20 a month no up front, but now they have two packages, blue or gold, and one is a little more. You can also add on packages such as sports or news or childrens for $5 a month.
One key is for $20 a month you are allowed one stream at a time. So if you are watching a game, no one can watch a different show on Sling. The slightly higher package now comes with 2 streams to solve that.
But of course if you have Sling at $20 a month, it allows you to use watch ESPN. So basically you could stream the game over watch ESPN, and you wouldn't be using the Sling TV stream, which means another person could still stream through Sling while you stream watch ESPN.
I rarely watched a game on Sling, instead I used watch ESPN. I have a Chromecast attached to my TV. I started the game with the watch ESPN app on my I pad, then cast it to my TV with the chromecast. Now my computer sits near my TV, so I would also have a HDMI cable going from it to the TV. Some Saturdays I would start one game on watch ESPN, then I'd start another using Sling and mirror that from my computer to my TV. Then start a third game on over the air TV like ABC. I'd now have three games going at once. I'd watch the ESPN game, but could see my computer monitor if anything was happening on the Sling TV game so I could switch over quick to see. Or just switch during a commercial. And every once in a while I could take a quick look at the ABC game.
Now if you really want to confuse yourself with too many games at once. Watch ESPN allows you to run 4 games at the same time, splitting your TV screen into four smaller screens. Most people think of watch ESPN as something to use with your phone when away from home. But for me with chromecast, it's just the way I watch all my football aside from over the air.