I see these are XML files of about 120MB in size. Zipping them only reduced them to 42MB so you are asking for far more which would mean you would strip out all the XML leaving only the data leaving it to not be a KML file and still far from your 5MB size.

What you could do is to edit the file to 5MB files but since I don't know all the reasons for your call here, I can't offer other ideas other than no, you won't be doing this.