coming from another southeast boater, stock up on B12 and think nantahala with sunshine in the early spring with a chance for cold rain...
drytop is mandatory... drypants should be too but you'll probably see me trottin' around in board shorts and a thermal layer unless I'm on something more remote. It might be 80 or 90 during the day, but it might get to 40 or 50 before you take off (and you're in snow melt... which granted is still warmer than the nantahala sometimes).
take everything you have and feel it out when you get there, but DRESS FOR THE RIVER... not the parking lot or hike up
you can always wear less next time.