This is the approach that I use as well. I have a folder specifically for my iPad. I resize the photos for the web - a small JPEG of roughly 1000 pixels on the long side and a medium to lower quality setting. The files are around 100-200kb.
A different approach is to use an Eye-Fi card in your second card slot. Write small basic JPEGs to that card. Using the Eye-Fi card you can connect to your iPad via the wifi connection and immediately see images on your iPad while you are shooting.