If you mean the black fabric bag that's shaped to fit inside the bow, then yes we have one. It does what it says on the tin. Probably not the highest quality bit of kit, but ours is still going strong after 4 years. It fits well in the bow of the Volaire & is great for stuffing all the bits that normally roll around in the bottom of the boat. We keep the anchor/tools/bailer/sponge/torch etc. in there. It originally came with 4 glue on buttons that you're supposed to stick to the tubes to fasten the bag securing straps to. We just thread the straps through the grabline splices & it works ok. As for impinging on the fuel space, I'm not quite sure of your setup, the bow bag is in the pointy end & the tie down for the fuel tank is at the transom. That said, we use a Zodiac Milpro fuel bladder that hangs off the port side grabline, so it's out of the way anyway.
Overall, we're happy with the bow bag, it does a good job & it's not failed us.