sizing terrain

so im working on a tornado game and right now and im making the map. so in my game i have a camera that i can zoom in and out of the tornado and around it during gameplay. my problem is when playing with like the ef4 and ef5 tornado they are pretty large so the camera has to get kindof up into the air to get a good view of it. but the problem is when i do so i can see the end of my terrain. my terrain is 20000 x 20000. how can i make it so even when i zoom out it still looks like an endless terrain?

@Jdogmaster

I recommend playing around with the camera settings. You can change the far setting to something lower. You could even change the field of view setting. There is a lot you can do to fix that. You can even make the terrain adjust its size to the camera which would be a bit more difficult.