How to Apply Very Large Texture to Terrain

Hello,

I am trying to create an environment in Unity that is a replica of a real life location. Currently I have a terrain that I created via a 3D mesh from Sketchup that I ran through Object2Terrain (http://wiki.unity3d.com/index.php?title=Object2Terrain) as well as a high resolution satellite image of the location (about 15000 x 15000 pixels). The issue I am running into right now is that I would like to apply the image as a texture to the terrain but due to limitations with Unity I can only go up to 2048 x 2048 pixels which is resulting in a very blurry texture.

What is the best way to approach this issue? Other similar questions to this that I have seen have recommended splitting up the terrain, texture, or both, but they do not give a detailed explanation on how exactly to do that.