The bodies staying around is a good idea, but as we still do not know how exactly the looting system works (do you have to actively search the enemy player's inventory etc), or the TTK, it is too early to determine the length of the log off timer. It also doesn't solve the stealth player issue could exist (sit in stealth, gank someone, stealth, alt-f4 before people find you). I would err on the side of a long log off timer, as this is always fair; plus encouraging people to log of in safe zones is always a good thing. A short log off timer is game destroying (see games like DayZ, where people log off all the time to try and avoid dying, and often succeed), and a long log off timer is pretty much always fine (see EVE Online). I would hope that the game devs would not sacrifice fair PvP at the altar of convenience for those people who do not plan ahead and want to log off in a dangerous zone.
Besides, in a looting game like this one, people should get used to the idea that all their gear and items are just consumables, you will lose it all eventually except for your knowledge, and any recipes you've learned for crafting (unless you play permanently in safe zones as a beast of course, in which case that is part of the core gameplay and I consider it perfectly fine. Even then however, there is a tiny chance that you could be looted by a gang of demons who finds you and kills you in the safe zone before the debuff kills them).