[Jim]

A few points:

• Klutz, the ring of Gaxx allows the user to cast invisibility, not improved invisibility, therefore the +4 AC bonus here won't apply
• Six, the Girdle of Glory provides a +3 AC bonus against slashing weapons only, therefore this can't count towards base AC
  

  What dex gives you a -5AC bonus? If 20, might be able to achieve -5 by BG1 import of race with natural 19 dex

  The next AC bonus due to DEX occurs at 21. The only ways to get a natural 21 DEX are:
• Start BG1 with an elven/halfling character, 19 DEX. The tome will boost this to 20. Then, in BG2, you could get a bonus point to your DEX in hell (provided that your primary class is a thief) to make this 21. There is also potentially a further +2 DEX that can be achieved in ToB (one of these again assumes thief), making the best natural DEX 23 (and the next AC bonus point isn't until 24 DEX)
• Start BG2 with an elven or halfling character, 19 DEX (either as single, dual or MC thief). You can then get +1 DEX in hell, and a further +2 DEX in ToB, granting a maximum of 22.