Well what is your goal?
Are you wanting to pack more stuff? Go on longer trips? Fish any?
I'm all about adding to the conversation, but sometimes you talk us into showing you this stuff then proceed to tell us we pack too much crap that you wouldn't pack...I mean no real offense, I'm just picking at you a little.
It mostly depends on the size and storage space features of the kayak.
I usually put things behind me if I can. Most kayaks have space directly behind the seat.
I do have a small space behind the seat, but further back mine has a bulkhead behind the cockpit and a mostly waterproof access door on top the rear deck, pretty standard feature on larger Kayaks, and I have a 12' angler style sit-inside. It's not very handy to get at on the water, but I can do it if I have to. I don't usually put anything in there I think I'll need to get at while floating if I can help it.
Even my 9.5' rec kayak has ample room behind the seat, no bulkhead but all that space behind the cockpit is fair game. It's not easy access but can be done on the water if you do like you said, put it in waterproof bags and leave yourself a way to pull it closer to you. Behind you would keep it out of your way.
Like you already do, using waterproof dry-bags for everything is a good idea. They conform to the space they are in better, and leave some air in there and they float, or like you I usually fix them to the kayak in some way so they will stay with it in the even of an unfortunate mishap.
Some kayaks have deck rigging. I've found that best for things that are small and I need to be at arms reach. I used them until I got my angler kayak. It has a "dash board" that is like an organizer tray on the front of the cockpit that holds a small tackle box, and can hold a fish finder, but I use that space for my camera since it has a padded bottom. I find it's the handiest feature since it gives you a spot to set things while you work on it, then can put it all away when your done.
Another nice feature of angler models, which you can install on other kayaks, is the paddle holders and rod holders. You can get all your gear strapped down for moving the kayak or when cruise paddling.