You could say I'm quite an avid minecraft player, so maybe I could be of some assistance? I've made plenty of custom maps before, and it would be fun to do another. By the way, by 15,000 do you mean 15,000 blocks? Well being that a normal minecraft world is infinite thats quite small, and in terms of a custom world you can scale it to any degree you would like, which makes large maps very easy. But, I digress. Back to your post, I'd love to help