I use the Stohlquist Fisherman PFD, I bought the size Universal Plus and it adjusts so far out I don't think it would be an issue. OEX is a retailer and they probably have it in stock, go try it on its a great vest. I don't see anything wrong with the Kokatat Bahia either get what you like.
The seats you are comparing I strongly recommend the GTS Expedition, you cant get a much more comfy seat. I haven't heard of the gone fishin seat, it looks like they focused on storage and not comfort (the seat pad looks uncomfortable).
I cannot stress enough the importance of a good seat and a good paddle. You can cut corners in other areas but comfort and adequate propulsion will keep you on the water longer and you will have a much more enjoyable day.
