You have a feat on 6; I strongly suggest starting with Rogue 3/Swashbuckler 3 so you qualify for Daring Outlaw as your level 6 feat (and start with Penetrating Strike). Also, if you dip Cloistered Cleric, consider Knowledge Devotion ACF over Knowledge Domain; you'd be able to get bonuses vs. creature types depending on your Knowledge-check vs. the creature type. Would make up for the lost BAB.

Craven simply requires Sneak Attack and no immunity to Fear. You get -2 to saves vs. Fear, but add 1 point per character level to any Sneak Attack-damage. And strongly consider the mentioned Darkstalker [LoM]; it's the only real means to be able to flank creatures with all-around vision and to sneak up on Blindsighted creatures and such; in other words, you get to be useful regardless of your opponent's senses.