I assume by Despot you mean Paladin of Tyranny? Or is this a different class I do not know about?
Ruby Knight Vindicators indeed make some of the best tanks in the game. However, cleric spells really help maximize that, so I am not sure if taking more levels of crusader or the paladin of tyranny dip is worth it.
Also, are the three LA you are getting free or at least can be removed with buyoff? Typically LA is not worth it.
Crucian start with 3 humanoid HD in addition to the LA, further slowing your progression.
Here is a pretty stand RKV tank:
Cleric 4/Crusader 1/RKV 7/Anything, but divine casting is best.
For feats:
Planning Domain to give you Extend Spell
Persistent Spell
Divine Metamagic: Persistent Spell
Combat Reflexes
Standstill
With the ability to have your buffs last all day, and with Crusader's ability to deal nice damage and heal a little all day, you are a wonderful tank. Using Combat Reflexes, Standstill, and Thicket of Blades stance you can stop opponents from just moving around you to hit your squishier party members.
Mineral Warrior is indeed a very nice template for a tank. Good damage reduction that will matter for many levels. However, it gives a penalty to charisma which you need for more turning attempts.
Half Minotaur from Dragon Magazine is also LA+1 and makes you bigger by one category (up to large) this is useful for extra reach so you can stop your opponents from further away. I suggest ignoring the text about getting MORE attribute scores due to getting bigger because that part makes the template overpowered.
Draconic Template is unexceptional, but it gives bonuses to Str, Con, and Cha which are all stats you need. Also +1 LA.
Human is probably the best base to put these templates on. Extra feat is very useful.
Also note that because your non-initiator classes count as half initiator level, taking levels of crusader level may allow you to start with higher level maneuvers. In the cleric 4/Crusader 1 entry I mentioned before, your crusader starts with ability to pick second level maneuvers.