Tear Aid tape did the trick for us on a March Grand trip, lasted the entire 28 days. It's stretchy to some extent, so perfect for dry suit gaskets.
Is handy for patching boats too if the repair isn't too big. I tore both a neck gasket, and a wrist gasket on my 10 year old suit in the first week. Used the tape and it held like a champ.
I was told years old that a dry suit should be called a comfort suit, so I cut my neck gasket a little on the big side, the one time I swam the pressure of the water compressed the gasket around my neck and wrists, no water entered.
My 2 ¢, your mileage may vary