It's a lot further than we like to drive in one day. Like KO we usually stop in the FL panhandle, near Pensacola the first day out. And we are a 120 miles further north than Orlando. We used to really push it on the first couple of days before I retired and we lost the vacation time pressure. We would commonly make it into Mississippi or further. But those were long days on the road, stopping around 8PM and that was with picking up an hour at the Eastern/Central zone change on the Apalachicola bridge. You -lose- an hour going east.
I see it's almost 700 miles from Austin to Gulf Shores. And you have that slow drive thru Houston. That will cost you 60-90 minutes of driving time.
BK