I'm looking for an event similar to OnLoad(), but fires even if the object is disabled.
Essentially, an event that will play whenever the player gets within a certain distance of the object. Is there anything like that exists?

You could put a trigger over the object and use an OnTriggerEnter() or OnTrigger() Event. Not sure what exactly your trying to do.

There's a ship, initially disabled. When the player approaches the ship (IE when they getting within the distance it'd normally be loaded at), the ship is enabled and begins to move.
The only hard part is finding the event.

Actually, here's a question that might help. What's the length and width of an exterior cell, in Skyrim units?