Hooray for you (and hopefully for the SIL).
My husband HATES receiving gifts, unfortunately I like giving them.
One year I found something very special for his birthday. I know him well enough that if I had wrapped it and presented it to him, he would refuse to open it (yes ... REFUSE!).
SO .... I went to his shop and found an empty box that he had received some machine parts in via UPS. I left all the shipping labels on it, knowing he would see the label but not scrutinize the date or anything - he would just see the vendors name as the shipper. I packed his gift and left it at the front door where he usually finds his UPS deliveries.