If you were using 3/4" pope I would do the same as Mike. You only need an 1/8" groove in the top and bottom sheets and it won't need to be very wide. It also doesn't need to fit the curve of the pipe. The middle pieces jammed against it will hold it place. This doesn't need to be as complicated as I think you think it is.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.