OK here goes...
I presume an alternate wife for boondocking is not the answer??
Your TV uses 60 watts at 120 volts AC. 60 watts at 12 volts ia 12x5amps=60 watts. Nothing is 100% efficient so lets allow 10 amps draw from your deep cycle battery.
If you check the specs on the battery it will probably say something like 100 amp hours or maybe even that you can draw 20 amps for 5 hours.
If it says 20 for 5... you can probably draw 10 amps for 10 hours.
In a perfect world that is.... new battery, warm day etc etc.
If it says 100 amp hours that's 1 amp for 100 hours or 10 amps for 10 hours....
Again only in a perfect world.
Nip down to Canadian Tire and buy a 15 amp solar panel, for about $150 $CDN or pop over to Costco and buy the Coleman solar kit for $399 $CDN. It has 45 watts of solar and a charge controller all included. Then you have TV all weekend (if the sun shines).
If not...then you must amuse the wife