Proper shell layers on earthbag dome in zone 7b

I live in zone 7B where we get about 48" of rain. I'm reading up on all this earthbag awesomeness but the layers have me stymied.  I've attached an image of what I'm thinking.  Basically my confusion is that I think I need to insulate the dome, and I'm thinking of using wet-sprayed cellulose because it is greener and more economical.  If I spray it on the inside of the dome and then plaster, cool because the earthen plaster will probably adhere ok to the cellulose and look good.  Then I can protect the earth layer on the outside with a direct application of concrete stucco.  If I put the insulation on the outside, won't the weight of the stucco crush the insulation?  If I don't use stucco, how else can I protect the cellulouse when we get 48" on rain per year?  *brain melting*

I have a shop with the wet sprayed cellulose. It is not really something I would attach anything to. It always seems to fall off at random. Honestly, insulation is a must and also one of the most expensive aspect of a good building. It's also not something to skimp on.

I spray my own close cell (water proof) insulation. It's a hot nasty job that requires a proper voc filter mask, but saves a lot of money. You might want to look into a diy application on the outside of the dome. You could paint it or the synthetic stucco that they put over styrofoam sticks and does not crack on building exterior. http://www.sprayez.com/c-57-cartridge-material.aspx

That's a great link, Dan. Thanks!