What does that mean?   

Well, it means (paddler's) feet and flotation will be overlapped.  I guess that will work for while.   

   What size floation bag.

NRS has bag lengths of 31" to 47" in pairs. So for a 31" long bag tha leaves 64" left for the paddler and gear.

This is the set that CLC sells.  As I said it will work for a while but one of my paddlers is already that tall.  I haven't put any foot braces in at this point but I don't think this bag will work if I do.  I guess I will have to carve a foam plug for the bow at that point.  Note: this is the WD 8   

   Perhaps you could take a couple of rolls on the pointy end.  Tape them down and basically make the float bag shorter?  I am not sure of the profile of the bow and stern of the WD 8 but I think it may be wider and shorter than what the bag was designed for and the above might work.

Ed

  I use a Watershed brand 'Salmon Stowfloat' dry float bag on my Wood Duck 12. Plenty of room and great waterproof storage.

���NRS often refers customer questions concerning float bags to me. People always ask what bag is right for an xyz kayak. My answer is usually the same, "I've got no idea what an xyz kayak is." I tell them to get a tape and measure the available space. Then order the bag that fits those dimensions. Your paddler dimensions are a real unknown. But figure into available space.

Then too look at available canoe float bags. Check out Paddle.net for suppliers. It's easier than modifying the paddler.