Determination + Grace + Iron Reflexes?

I have IR and I planing to boost my armor with both auras but Determination and Grace consumes 60% of mana, so I can't use both at same time. The questions are:

-Is that a implicit restriction that can't be changed?

-Or is there a way to use both together? (with support gems, pasives or something I missed)

Reduce mana gem is a must for auras; you can complement it with aura passive nodes.

there are also passives in the tree that reduce mana reservation as well as uniques.

in my aura scion i run 6 auras atm and if i had the aura shield i would run 8.