I wouldn't use a file, or a dynafile, both sound like way too much work, plus I don't see the dynafile making a rounded trough like he wants.
Seriously, the alumahog bit will make very short work of this, he is coming over Saturday...
Based on some of the comments here you guys way over think these things...
Let us know how it goes and take some pictures for the love of Pete too.
Better yet, invite us all over to watch and have some coldbeer handy too.