Good news! When the laws made it legal for parents to home educate, by default if they are trusting the parent to educate their child/ren, they have to give them the trust/right to know and decide when that education is complete! So you do not need to have a GED.
Parent issued diplomas are legal in all of the states of the USA. If you were to reach some wall of some one not willing to accept your diploma, you can contact HSLDA lawyers and this can be fought, since it's federal law now for parent issued diplomas to be accepted just as legally as school issued diplomas.
HSLDA has a wonderful list of answers to almost all high school diploma questions.
HSLDA Diploma answers!