Look around the web, there are stems longer than 130mm available, often cheaper than a setback seatpost. Do you feel cramped in your current set up?

Also, it is not advised to use a setback seatpost to address handlebar reach issues because the purpose saddle setbacks are to put your body behind the hub of your bike, which means distributing more weight to the rear of the bike.

If you can, take a picture of yourself on the bike from the side with your cycling apparel on. You could post it here or compare position with other pictures of track riders or road riders you can find.