not happy with the bucket seat that comes with the raft.

I dont use it at all. Instead, I use a small 3" thick inflatable Thermarest (40th anniversary edition, 17 oz). I fold it in half and shove it in the back of my cockpit. It is a 100% improvement over the bucket seat. More reach, agility, maneuverability, punches through holes better with the longer stroke, better bracing, better view, more comfortable, no more rock hits to my butt, doubles as my sleeping mat. Besides being lighter, what are the benefits to the bucket seat?

On a side note. I also use my large inflatable pillow shoved in the front to use as a foot brace. So far, I havent had any problems with yard sales while flipping in stuffy holes and V- whitewater, which I find to be the limit of my comfort level when creeking with my set up. I havent installed thigh straps yet.