My suggestion would be one of two things:
1) Instead of taking the Sponsored Magic power -- which is spellcasting, pure and simple -- use the fact that you're sponsored as a valid excuse to buy other powers. For example, Echoes of the Beast would be a good start, as would Inhuman Strength. Take those refresh you were going to spend on Sponsored Magic and spend them on powers like that (and on Marked By Power) instead.
2) As an alternative, make use of the "Temporary Powers" sidebar on YS92. Give yourself Marked By Power, then spend Fate to give yourself suitable powers temporarily. This will start costing a lot of Fate, I think -- but it's probably fair to allow you to use the Debt rules to pay for these temporary powers. I think the -1 for the Marked By Power is enough to cover this "advantage". At worst, you might charge for an additional -1 power to 'establish a credit limit', but I think that would be overkill unless it carried other benefits.
PS: Damn all you fast posters!