If my sig is in a spoiler, would that be ok?

No, the image still loads whether it's in a spoiler or not, so it would still oversized in terms of file size. If it was only oversized a bit in terms of dimensions, then it might be alright, but since it's not then you can't do that.

Looking at your signature, I recommend you keep one of the larger images and one of the underbanners. That combination would fit within the signature rules.