If you're going to be doing stealth in an undead-heavy campaign, a shirt of wraith stalking (Magic Item Compendium 216) is nice. It gives you a variant of hide from undead that doesn't allow intelligent undead a save, usable at will for 6,000 gp.
Another good item for an undead-heavy campaign is a truedeath crystal (Magic Item Compendium 66). It comes in three varieties, each of which includes the benefits of the cheaper ones. It gives you +1d6 damage against undead for 1,000 gp, also makes your weapon ghost touch for 5,000 gp, and also lets you deliver critical hits and sneak attacks against undead for 10,000 gp.
You mention filling the trap-monkey role. Are you using the trap expert alternate class feature (Dungeonscape 12)?
Is hunter of the dead just in there for detect undead at will? You could instead take a level of paladin with the detect undead alternate class feature (Expedition to Castle Ravenloft 208). You could also pick up corpsestrike (swift action, ignore DR of undead creatures for 1 min./level) 1/day and undead knowledge (+2 bonus on knowledge (religion) checks concerning undead) with the eternal order substitution level (Champions of Valor 39).
Warforged are immune to poison, sleep effects, paralysis, disease, nausea, fatigue, exhaustion, effects that cause the sickened condition, and energy drain. With 5 levels of warforged juggernaut (Eberron Campaign Setting 83), you can also become immune to nonlethal damage, critical hits, mind-affecting effects, death effects, necromancy effects, ability damage, and ability drain. That covers all the same things as skullclan hunter and then some with fewer levels.
Alternately, 10 levels of pale master (Libris Mortis 47) gets you immunity to disease, nonlethal damage, stunning, poison, sleep effects, paralysis, death effects, critical hits, ability drain, energy drain, and damage to your physical ability scores. This doesn't cover fear and damage to your mental ability scores, but it covers some things skullclan hunter doesn't, and it also advances arcane casting 9 levels.
As a third option, 10 levels of bone knight (Five Nations 117) gets you immunity to stunning, nonlethal damage, critical hits, sneak attacks, poison, sleep effects, paralysis, death effects, fatigue, exhaustion, damage to your physical ability scores, ability drain, energy drain, and death from massive damage. This doesn't cover fear, disease, and damage to your mental ability scores, but it covers some things skullclan hunter doesn't, and it also advances divine casting 9 levels.