Unload big textures (from Resources folder) from memory

Unity Engine
1

I want to create an iPad-App where I show some 360°-renderings of architecture-scenes by using a skybox-component on a camera.

The skybox materials and its textures are located in a “Resources”-folder.

This works fine, but now I have to ensure maximum quality with minimum videomemory.
(I use 6 x 2048/2048 automatic compressed textures per material, 1024/1024 appear unsharp on iPad2).

My problem is, how can I definately unload the textures/material from memory when I switch to another panorama?

Would you change anything in my Cleanup()-function?

function Update () {
	
	if(Input.GetKey(KeyCode.Alpha0)) {
		GetComponent(Skybox).material=Resources.Load("Pano1/Pano1",Material);
		Cleanup();
	}
	
	if(Input.GetKey(KeyCode.Alpha1)) {
		GetComponent(Skybox).material=Resources.Load("Pano2/Pano2",Material);
		Cleanup();
	}
}

function Cleanup(){
	Resources.UnloadUnusedAssets();
}

And, is there any way to check if cleaning up really works?
I also read something about cleaned textures leave a gap in memory…

2

Yes use the profiler. When I use Resources.UnloaUnusedResources in my app with the profiler on, you can see materials, textures and whole memory footprint drop.