I raised the original plastic PA seat (the older style with the attached rudder handle) by attaching it onto a 7" swivel pedestal from Walmart.
I can now turn around 180 degrees and access the live well from above while still sitting, which is really convenient. The reason I bought pedal kayaks in the first place was due to a shoulder injury which makes reaching behind me (and paddling a long way) almost impossible, so this mod was a life saver. The rudder handle is still attached to the seat and there is plenty of play in the cable to turn around without pinching the cable
The raised seat is also great for casting and gives me a better view of the flats on Tampa Bay, and the kayak is still really stable. I can also fish off the back or sides of the kayak now, and can play a fish all the way round the kayak
Total cost was a little over 20 bucks and the swivel pedestal holes lined right up with the holes in the seat bottom, so installation took about half an hour total. I added a sheet of 3/4" marine plywood I had laying around underneath for weight distribution since spinning around might put some unforeseen stress on the kayak and seat mount. So far so good!
https://imgur.com/uU53niihttps://imgur.com/dPLAir5https://imgur.com/gP0jBna12-11-18 update
So after almost six months of using the raised swivel seat I can tell you there's no way I would ever go back to fishing with a lower fixed seat.
The added height and maneuverability makes an amazing difference when fishing. I honestly don't know how I would ever enjoy kayak fishing again without it. I'm getting ready to add the same raised seats to all three of my Native Mariners, and I'll be taking a couple of the kayaks fishing in Weeki Wachee in a couple of days. The Mariners will all have a 2-pc pedestal which I will be able to adjust the height on.