Hey Guys,
I have seen the surf do some strang things and I reckon there is nothing to say that any gizmo will help you out in the surf.
Seen loads of kites go down in 1-2 foot slop and been literally ripped to pieces

and have dropped my kite on the bommie at Margies, pummeled under a 6 foot crashing wave , two foot thick lip straight onto the kite, it turned the kite inside out, it relaunched (inside out) flew up 50 feet and turned the right way out in the middle of the power zone with tremendous force, and escaped with only a tip strut being disconnected from the LE

. I couldn't believe it!
Luck is the biggest contributing factor when dropping your kite in the surf, only luck. Dunno whether 5th line is good or not in the surf, but if it makes you fell lucky, go for it. I reckon when your kite goes down, you're at the whim of Neptune and Huey.
Good Winds