Jeremy.
Take a 1*2 pine board 6-8' long and drill as many 3/8" hole/divots in it as you think you will need, then attach it to the wall in as big an arch as you can get it to bend into, perfect tiller of course
Then in a fan shape matching the pine board put dowels in the wall, then place the tip of the arrow in the divot and lean against the dowel. Easy to add, remove or redesign the pattern. If there is to be any vibration or banging on the bench you could put a small rubber band around the arrow and the dowel to hold it in place. Start in the middle and expand to the outside of the arch.
Lots of pics of the room when you are done with what ever design you go with.