Here in the Netherlands we fish half our season also with cold conditions. I tried a lot of different clothing in my kayak to fight te cold. For Norway and Sweden fishing they sell floatation suits over here. Those are not good. You can not move in those suits and the aren't comfortable at all in the kayak.
Don't know in Fahrenheid buth in Celsius it's somethimes below zero and the water is freezing into ice. Hope you understand the tempature in Celcius. In your profile I can't find where you live so don't know what rating you use.
The best option in my opinion is a sailing drysuit. Those are build to use during sport and above the water. Not the ones scuba-divers use. They are not made to move a loth. Also the surf Drysuits in Neoprene are no option.
Have a look at some brands around. I and a loth of friens of mine use a Code Zero drysuit from Gul marine. Bith there are several brands who sell those kind of drysuits. They are comfy in the kayak. If you puth more than one layer under it you'll be fine. The real problem with - 6 degrees is your feeth. I never had any problems wearing my Dryssuit, base layer and radiation undersuit. Besides my feeth. My bleeding stops in my feeth as soon as I hit the kayak during winter.