S.G.
First off good luck in your new adventure! I would make it a point of setting up a specific time that you will be contacting him. The minute he leaves put a postcard in the mail. Also you could try taking pictures of what it is your doing, packing, getting everything organized. You might have him before he leaves help you pack some of his own things so that he's aware of all the work that has to be done and maybe just maybe he can understand that this process is going to take a while. Send those pictures periodically. This works great if you have a digital camera and internet access. This worked like a charm when my husband and I went on a very long very far away vacation and we left our sons