I think the stealth was tough but fair. Speaking from experience, it is possible to sneak through even the larger compounds if you pick the right path. But yeah, the game doesn't accommodate you if you're not taking it seriously. That's a part of the overall design philosophy, though, and its unrivaled spontaneity - things are meant to go wrong in Far Cry 2.

When it comes to the guard posts, it's really best to stay away from them and "go off the beaten path" to make it to your objectives. That's how you find the hidden diamonds and see all the beautiful hand-placed vistas. I really only hit up the outposts for resources, such as when I'm low on syrettes or need to restock my grenades.