option to drop a chest full of items

drop: CHEST@[DEFAULT] for players could act as a simple "tombstone" (will include in example config along with a comment that the "Tombstone" plugin is more fully featured)

additional: expiry time? (this might require timers which could make our plugin a little "heavier" - so maybe not)

If you're doing it for chests, then why not for dispensers and furnaces as well?

Also, a chest cannot hold a player's full inventory; players have four rows while chests only have three. What would happen to the overflow?

True - this code would be also used for other containers.

Full inventory can be stored in a double chest - ala. Tombstone - trickier to deal with then though as there are situations where you cannot drop a chest - perhaps I should just disable this feature for players and let them use Tombstone rather than offering a half solution.

Primary purpose is for "loot chests" from mobs.

Yeah, I can see the point in that, I guess.