I looked into this a while back.
You're likely going to have to get custom made seat brackets.
After a lot of research, the lightest weight seats that I could find that still had an adjustable recline feature were the Cobra Misano (full carbon)
I need/want reclining adjustment, because otherwise it makes putting the 6-point belts in and taking them out again kind of difficult. If you don't care about adjustment, you can find a lot of seats that are even lighter. Nice thing about the Cobras, is you can get them in just about any custom color/leather/fabric you want. Custom embroidery also available. If I get some extra $$, they are still on my list of "some day" upgrades.
Cobra Seats
One thing you will have to deal with is the seat sensors for the airbags. The stock seats have sensors built in to the seats. You will need to disconnect these sensors and "jumper" the connection so that it gets a constant positive signal. A good electrician should be able to help with this.