Can you show an example of how page looks like? Maybe it could be split to smaller objects and instead of making one big image, recreate it in C2 from smaller images.
If that's not the case, you can always use one image for one layout and make each image separate object. So on each layout only one image is loaded into a memory.
Anyways having 45 full hd images should not be a problem, but if there's another way to go then you should definitely go that way.