I skimmed through the PDF. I like the idea.
I'd like to see a defender variant of the ranged fighter concept someday. Many of the class features of the regular weaponmaster already work with ranged attacks, they would just need something to replace combat superiority that works at range, perhaps some kind of 'cover your allies' ability that let you interrupt enemy attacks, similar to the way the ranger encounter power disruptive shot works.
Further support via some ranged fighter at-wills and other intermediate powers that can key off Str or Dex would make for a highly mobile, skirmishing fighter archetype that's still a defender, and distinct from the ranger (with its striker-role and previous edition flavour baggage).
Your idea has given
me ideas. So, thanks!