I've been toying with this, and I think it should be 3 spells:
Creating the construct: I'd say that this is a spell of around (your refresh level)+4, to make an ectoplasmic construct. You'd probably want to increase this for believability, probably into 5-10 more shifts of power. I'd actually set the base difficulty to see through the guise as how many ever extra shifts over the base difficulty you add. This requires several token parts of yourself (fingernail clippings, hairs, blood, ect) - the more ties, the stronger the connection.
Warding your body: This is nothing more than a block-type ward versus possession for your body. Given the relative ease of making circles to ward out spirits, this is the least complicated part.
Transfer your consciousness: This is probably the most difficult, and relies on grey-area necromantic principles. It requires [enough shifts to take yourself out, assuming no resistance]+4, and in game terms really just applies the aspect "In my Golem body" to you.
Effects: In your golem body, you can act pretty much as you do in your normal body (your powers and skills are accounted for in the cost of the body). However, strong wards, running water, countermagic, ect can knock you out of your construct. This is normally fine - your spirit will bounce right back into your body - but can be a serious problem if someone erects a ward around you before destroying your form, as your spirit can get stuck. Also, enough of "you" exists in the golem form that you can still be targeted with mental attacks, curses, and the like. Lastly, while your golem could use your focus items and such, it sucks if you lose those due to the golem's destruction. Lastly, you are bound by wards like a spirit, rather than a mortal.
The advantage is, of course, people dealing physical damage to the construct can't really hurt you. However, any real physical damage to the construct is translated into mental damage on you, meaning that it is still worth conceding well before the golem is fully destroyed.
A fourth spell can be made (difficulty 4-8) that simply destroys the physical tokens of you that are embedded in the golem, once the golem is destroyed or abandoned.
Due to its power, the spell costs 1 fate point to activate, and lasts until broken, abandoned, or sunrise.
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Any thoughts? Should the spell really require a bucket of fate points (which the caster will not have on a regular basis, given that casters run at low adjusted refresh?)