You will have a GPA if you take any ECE or DSST exams at all. You need at least 30 graded credits (ECE or DSST or courses) to qualify for academic honors. You will need at least 30 upper-level credits to get your degree anyway, and since none of the CLEPs qualify for upper-level credits, you'll end up taking ECEs or DSSTs or courses for all of them. I don't see how you can go wrong.

-Gary-