Here is how I join the book matched maple boards together.
I get a piece of flat mdf (I had an LP template downstairs and that worked fine) and I two-way tape one of the maple boards down to the mdf. Then, I run another strip of tape on the mdf for the other board. This keeps the pieces flat and in place while I apply the clamps.
With the hide glue prepared, I run a hot iron across the area where I am going to apply the glue.
I apply the glue.
I press the boards together and apply the clamps.
After about three or four minutes, I remove the clamps and sandwich the boards between two pieces of mdf. This keeps everything flat (even though it will be planed again). As the moister evaporates from the glue, it will continue to suck the pieces together and become glass hard.
Sincerely, Scott