solution is pretty easy.
get some 1/4"thick flat steel. I got mine from lowes.
put the seats on the flat steel toward the front and mark your mounting holes. these will be your OEM mount position so the rail extensions mount the same as the seats
Figure out how much extension you need. put the seat on the rails as far back as needed. 4" or so and mark the spots and drill it out.
drill those out.
Then get some bolts, washers and nuts.
Bolt the Seat rails in 1st using factory hardware.
then bolt the seats into the rails
here are pics of mine