Don't think Shield Skin works with a longbow.
How about this?http://nwn2db.com/build/?268161
Monk dipping for Wis to AC, Unarmed Strike and saves you on Armor Skin II, III and elusive archery (they don't work with monk) while keeping similar AC.
Ranger can cast Wild Instincts for uncanny dodge.
Note: Contrary to the feat description, Ranger HIPS works even indoors
Monkey Grip allows gnomes to use longbows on this server.
You can thus race swap, at the cost of 1 feat, 1 AB and a 20% XP penalty, to gain up to 5 AC.
If you give up the trap disabling and ED/Conceal, you could build to a purely offensive archer, something like Ranger21/MM13/Elemental A 5/Monk1 for Bane of Enemies (+20 unresistable magic damage against favored enemies on this server) and EA bonuses to AB, AC and damage.