I very rarely use mods for this game and never played as a beast race character so was wondering are there any mods to enable khajeets and argonians wear full face helmets and boots?

No. Full helms are impossible in a traditional way, workarounds have been thought of, but I don't think anyone actually made any.

For boots, again, no, it's impossible that beast races wear "full" boots, but several people made shin guards of sorts, that is, boots that cover only lower legs, and not feet.

Another option would be to grab upright walking beast races, ala Oblivion, if you're into it. Don't hold me for my words, but I think it's LizTail's work. Those can wear anything that human races can.

For boots, you can use "Leggings"
They work just like boots, but still keep the beast feet. Adul's version is really nice. Found here: http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=7705

If you're going to play as an Argonian, I recommend http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=8294.

Khajiits can obviously wear them as well, they just don't look as cool in them IMO.

I'd love to see a compatibility patch for MCA 6.1 so you'd see some random NPCs in the game wearing those armors.

While not knowing exactly how MCA works, I suppose one could insert those armors into custom leveled lists and add said leveled lists to a number of NPCs. That's how I would do it, at least.

Is that something you might be willing to do?

A beast race character can't wear CLOSED helmets, although most open-faced helmets work fine.

Aside from the "spoilerish" weapons in Adul's mod, the beast leggings seem decent. He figured weight in "pounds", not in the roughly "quarter pound" unit that's used in Tamriel, so the weapons are all WAY underweight.

Sorry, I don't mod any more. You could probably find someone around here to walk you through it if you wanted. It's not difficult, just potentially time-consuming, depending upon how many NPCs you want to bestow the armor upon.