I am not that crazy about those perks. As someone mentioned, they don't work with dragon priest masks. Plus, you don't get the hidden 100 if you are not wearing armor, so your 300 with three perks and ebony flesh is the equivalent to 200AR with a full suit of physical armor.
Then, when you get Dragonhide, you don't really need the perks that much since they do not affect Dragonhide. That spell gives you an 80% damage reduction, which is plenty.
A lot of times, my mage will wear robes with a dragon priest mask and enchanted boots and gauntlets. With three pieces of armor, you get most of the hidden 100, plus some actual AR from the three pieces of armor (more if you smith it -- even unperked, you can get a good smithing bonus on your gauntlets and boots if you use fortify smithing enchants and potions and you smith before you enchant). Then you can cast your unperked flesh spells on top of that to boost it by up to another 100 with ebonyflesh.
You may not get quite as much protection this way as you can with three perks in Mage Armor, but you will still get a decent amount of protection, you get the benefit of the robes enchant, you can wear the dragon priest masks and you save three perks (five if you weren't going to perk Alteration but for the mage armor).
Wearing a pair of gauntlets and boots does not seem that out of character for a mage to me.