My Tank has an AC of -11 in BG1. I could get -12, but I don't like the Claw of Kazgaroth THAT much. ToSC has a Large Shield+2, allowing you to get -13, and if you do that and crank your Dexterity all the way up to 25, you've got an AC of -15. Which isn't as great as it sounds, as Critical Hits still get in.....just as they did when you were at -8.
My guy's wearing the same as Kaz's, except I use Drizzt's Defender instead of the Varscona (Longsword+2), I only use the Ring of Free Action when facing spiders (it's the Ring of Energy the rest of the time), and I use the Necklace of Missiles. (Man, those things are cool! The first time I tried mine out, I was outside in the city of BG, and accidentally toasted a few Commoners. WHOOOPS!

I hand the Girdle of Piercing and Boots of Avoidance out to my other guys--I'm ALREADY immune to arrows.