What can a melee focused Witch do to avoid dying instantly (apart from not being a melee focused Witch)?

A Player's stepping up to DM Skulls and Shackles for the group, and one member has decided she wants to be an Undine Sea Witch that punches people with a cestus.
We (me and new DM) have tried talking to her about the inherent squishiness of a witch, and the possibility of using a slightly different class that would get her the same or similar effects without getting splatted, but she's set on what she's built so now we're looking at ways to keep her alive without having to obviously pull punches.
I'm playing a cleric so I can make sure we're (she's) properly buffed and healed, but is there any early equipment we can dig up or build choices we can suggest in order to try and keep her alive until at least the Book 1 final boss?

Also, how well do aquatic characters and animal companions do in the S&S? Really tempted to line up a Shark Shaman as my backup character, but I don't want to find out further down the line that I just have a worse wildshape because turning into a shark is never useful.