That seat is near identical to mine. I also ride a DRZ400s and I have five discs missing in my lower back. With the stock seat I was in excruciating pain after 50-75 miles.
I snagged a used Russel Day Long seat on ebay with the same wing design. I have regularly done 300-400 miles in a day with no issue now. I feel that general seat design is a MUST for DRZs.
I will continue to follow your progress!