it's gonna be tough if you take fulltime college/ fulltime high school.
but it's possible

my sister is a senior and she goes to high school (semi?) full-time, (she takes ap class too)
and take four classes, 20 credits, at community college (normal fulltime takes 3 classes) because she changes her mind and wants AA degree with highschool diploma.
she also works part-time 4hrs/day. though sometime she called in sick and skipped .
she never has more than four hours of sleep. but that's what starbucks are for (at least that what she told me)
anyways, just as long as you know how to manage your time and schedule your schedule wisely (make sure you meet the high school grad requirement)
^i agree, see if some of your hs classes can be taken at college.. or if you're willing to work super hard during summer, you can take less classes now and more classes later. online/distance learning classes are pretty easy though (according to my sis). you might want to check that out.