BFR,

Some thoughts:

I don't have nearly as much leverage when sitting on a yak with my legs straight out in front of me as when I'm standing, therefore I can't cast nearly as far sitting in a yak as I can standing.

You aren't as high out of the water when sitting in the yak.

I assume that you are talking about salt water fishing. The wind blows harder over open water and it seems never to be blowing to your advantage.

My suggestion would be, use a long rod with lots of authority as you are handicapped many ways.

I've been using my Simms gortex waders for two years in the salt with no adverse effects.

Don