Hi Kerri,
You can keep both species outside and they should both do well in an outdoor enclosure in SA.
It is best to make an enclosure out of a smooth material so they can't climb it or rub noses and have it extending about 40cm below ground level, even though gravid female beardies are the only ones likely to dig its better to be safe than sorry.
Chuck some plants in for a cool shady spot and make sure its cat and bird proof.
EDIT: Forgot to add: make sure they have a sleeping area that always stays completely dry, beardies will often sleep in the open but shinglebacks will curl up under some leaves or a log which should be dry to avoid health problems.
