Since it is being tied it should be fine. But sure seems like it would be heavy! A sample would be a good idea. The only sewing hurdle may be attaching the binding strips through all that, unless you have a pretty heavy duty machine--again making a sample might be a good trial. If it is an issue you could use the "birthing method" and skip the binding. (Have not done this myself but there are lots of threads on it on this board). He seems to know what he wants so I bet he will love what you make him.