Punishment for AFK?

We've all had games with afk's, making it a frustrating 4 vs 5 where people surrender early, lose, enemy snowballs hard, and the game becomes not what people play league for, fun. Now of course, there will be SOME games, where people can actually play, but the rarity of that is negligible. But most people also have had genuine internet problems, causing them to dc. So on one hand, a too easy punishment would allow for trolls and others to afk and make the game irritating, but a too harsh punishment like banning people 1st leave would produce the same result. An interesting idea: People lose IP or RP(although this would be pushing it) when they leave a game. Having sufficient IP to lose would mean that the player has played a decent amount of games, and details could be changed but it would look something like this:

1. Afk'ed players lose the cumulative of the ENEMY's gained IP. So something like a range of 350-1000 IP, depending on IP boost and first win of the day.
2. At 0 or negative IP, (no, when people make an account you start at 0 yes, but not this time) the player is seriously punished, most likely a ban.
3. Ban duration would get longer and longer for every time IP goes under 0, OR ban duration days = how much negative the IP on the account went / 100 (number here is adjustable also, in fact this number could get larger per times the account has fallen below 0 IP), so if someone had 10 IP, left, enemy gained 500, negative 490 IP, so banned for 4.9 days or rounded 5. Additional Ideas:
4. If someone afks the whole game, or half the game, the amount of IP could be different also, say afk half game, then half IP loss, etc. Ideas? Suggestions? Constructive Criticism? Do you guys think this would work? Why or why not? Feel free to share!