I am travelling for several months with a digital camera. For security I would like to backup my SD card(s) every so often to another SD Card or USB stick. With that I will always have at least two copies of my valuable photos and videos. There's no need (and enough room) to store the contents on the iPad. I have seen wireless SD card readers. I wonder if these will do the job without copying the photos/videos one by one. Any suggestion or remark is welcome.