Since Excelsior is a legit school you should have no problems. To further enhance the status they are also title IV approved. In order to claim full time status you should fill out a study plan w/ EC indicating your schedule. Say for example you plan on taking 2 DSST's, one Clep, and one EC class for a total of 12 units. I don't think you can just go as you please but if you file a plan you should be covered.

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The best things in life aren't things.
~Brandon