ABANDONED. Adventure Novel trapped on island hides from bad guys in sarcophagus

[Cait]

I don't have many details to go on but here's what I remember...
I am looking for the title of an adventure novel that I read for a class in college back in 2002/2003. I remember the book was about a boy or a man who was stranded on some island and he had to build shelters and hunt to survive. There were some bad people on the island, they may have been part of a tribe of some sort. I distinctly remember this one scene where the main character finds a cave that has what I think is a sarcophagus in it. One time when he's in the cave, he hears the bad people coming and he hides inside the sarcophagus and I think he hears some important information. This book was not geared towards children, it was part of a college course called "The Novel Adventure" and contained adult book titles. I hope someone out there can help!

[Lobstergirl, au gratin]

Bump, I want to know what this is.

[Lobstergirl, au gratin]

Another bump. Cait, are you still looking for this?

[Lobstergirl, au gratin]

Possibly The Invention of Morel. It's a novella, or a very short novel, definitely adult, considered a classic. It's kind of adventure/sci-fi, but it's written in a literary style and the sci-fi element isn't revealed until the end.

[Kate (Feathered Turtle Press Reviews)]

The hiding-inside-a-sarcophagus part vaguely reminds me of a scene from Moonfleet.

[Lobstergirl, au gratin]

In "The Invention of Morel" the main character is a fugitive on an island. At one point he hides inside an alabaster urn. This is literary fiction so it might be taught in a college course. Nonetheless, there aren't enough similarities to know if this is the book, so since Cait hasn't responded, moving to Abandoned.