The key to mounting a keyboard tray is that you need at least 11'' of uninterrupted depth onto which to mount your track. There are keyboard trays that will work with less depth but you will sacrafice adjustment range. For more info on how to select the perfect keyboard tray for you, watch our video.
I received the chairs today and they are perfect. Thank you for your personal attention to my shipping snafu. In this day and age of the internet and push button instant gratification, we sometimes forget that the real value is not in a price that is 1% better. It's in the value added by empathetic people how really try to help. Maybe you should create a company tag line like "Real humans providing great human solutions."