William
If the aid stations are 10km apart or more then I would definitely advise you to carry a hydration bladder. The event is in July, and if it turns out to be a hot day you will be in a world of hurt if you don't have enough water.
No ultra route is ever as well marked as the organisers claim, so take "map and compass optional", to mean "map and compass necessary".
Having done six marathons you should be able to handle this event pretty decisively. The only way in which my 50k programme differs from my marathon programme is in that I will do a 15 mile run the day after my long run while my legs are still tired.
You could probably run the whole course if it isn't too hilly to be honest, but you have to read your body take note of the terrain and make your choice accordingly.