Rachel has a lot in common with Scarlett O'Hara (multiple husbands, enjoys the finer things in life, selfish) and yet while Scarlett is framed as a hero who shows the power of the human spirit, the other characters (especially Leah) mostly see Rachel as a whiny, bigoted Rich Bitch. Then again, it could be that Rachel is an Alternate Character Interpretation of the Scarlett character or the "Sassy Southern Belle" archetype she spawned in an anti-racist, post-colonial context (as opposed to how Gone with the Wind glorifies the slaveholding South).
Ending Fatigue: The epilogue is actually a sizeable portion of the book. It details the lives of all of the main characters over the next thirty years. The book really ends almost 37 years later with Mobutu's death.
Nathan. Yes, he's a complete asshole with few redeeming moments, but this is due to PTSD having turned him into The Fundamentalist, and he eventually loses everything and ends up as a crazy hobo.
Rachel. She's a Rich Bitch with few morals, but she was also left deeply disturbed by what happened in the jungle. She never adapted as well as Leah, never had the help that Adah and Ruth May did, and was mocked and belittled whenever she did try to change herself. She almost had to get married to the head of the village, her little sister dies, and she has to charm a much older man in order to get to safety; her family don't even seem to care what happens to her. It's also later revealed that she was left infertile by said older man.