A thorns pally wants to get hit. So, no shield, thin armor. However, there has to be some middle ground: I had one like this that I got well into act 3, but at some point the hit that killed the monster also killed poor Arjuna (pumped VIT and all).

I'd like to try this concept again. Any advice on how little is too little?

So, you either take that hard hit, or you die trying.

I recently started a Thorn Pally, and I'm going for as low of defense as possible without sacrificing items with useful stats.

I just avoide leaving my health very low. If it goes down below 2/3, I just retreat and chug a potion, or TP back.

I'd go with a rather normal setup in terms of armor and such, even considering using a shield. (especially when up against heavy-hitting stun-lockers like those vultures) The playstyle would be like a normal warrior, except you have the "bonus" of thorns damage. At the very least, you could use a low defense armor with a 2-handed weapon, switching to shields with varying amounts of blocking as the strength of your opponents varies.

I suppose if you're playing a thorns variant where EVERY kill (or as much as possible) must come from thorns, this isn't very good advice, but in terms of survivability I think this may be a solution.