The aura of sanctity alternative class feature (Dragon 349, p93) can give a paladin immunity to compulsions. It replaces turn undead though, which might be problematic if you were going to rely on sacred vitality for protection against energy drain and blood drain.
A
paladin of freedom gets immunity to compulsion effects. The whole chaotic thing may not work for you though.
The 3rd eternal order substitution level (Champions of Valor, p39) allows you to "ignore the effects of" negative levels from undead. I'm not sure if that includes ignoring the part where you die from having too many negative levels, or if it just means you don't take the penalties.
The font of life feat (Heroes of Horror, p122) gives you a save to avoid negative levels. With good fortitude saves, that could be quite helpful.
On a more unusual note, you could go with the paladin variant that gets favored enemy. There exist ways of adding your favored enemy bonus to saves and AC.