I don't like to charge or discharge too fast. IMHO, C/20 is great.
TV includes the sound system? And Sony probably has a dandy sound system.
100W is great for a selling point, but a standard factory car stereo usually peaks out about 12W. Probably usually uses less than 3W.
Brightness is adjustable? Not sure how much, but that probably knocks off another 50W at levels people like.
Leaving 150W? About 12A at 12V nominal?
One pair is a little light. 2 pairs is considerably more than needed.
I would probably get 2 pair. More storage (within reason) usually makes for a better performing system.
That should match up pretty good for the charging system too.
2 pair has other advantages too.
Less abuse, so they should last longer.
When they are old and only holding 70% of their rating, they are still able to do the job.
Meaning 2 pair now could be better than 1 pair at a time for the next 3 pairs. I know that sounds like an exaggeration, but it worked out far better than that for us at the shop.