For those who like them, there a lot of wraps which work, everyone seems to have their favorite - mine is Rescue Tape (Self-Fusing Silicone Tape).
It provides a little bit of "stick" on your hands to allow a firmer grip without impeding rotation of your non-control hand. If you use it, be sure to wrap a couple wraps of electrical tape on either side of the rescue tape, otherwise water will get under it and shorten its useful life.
Also, get good quality rescue tape, 20 mils thick (if done right I find the wraps last a few hundred hours of paddling time). The thinner stuff wont last nearly as long.
And as along as you are wrapping, perhaps add an index bump on the inside of each wrap ( I use 1/4" electrical tape wound around till I get the right size bump, then over-wrapped with a bit of wider electrical tape). This allows your hands to get in the proper position by feel alone.
Your real issue here though may be the "death grip" you are using on your paddle. When I was learning I needed to consciously remind myself to loosen my grip and flex my fingers on the return stroke (when your hand is moving forward), particularly in rough conditions. Otherwise, as you say, your hands will go numb, and, as this would be a repetitive stressor, you could end up causing yourself some lasting damage depending on how much paddling you do.
I just redid my epic small-mid, I'll try to attach a pic