I thought of this theme idea many moons ago. It proved impossible for me to make itself at home in a 15x15 grid, so I expanded it to 17x17 and, after many a trial and even more error, this is the best fill I could come up with.
Not the snazziest looking grid. Too many three-letter answers for my liking -- including some obscure names and a few even more obscure abbreviations -- so I tried to make the solution completely get-able by aiming for a medium-ish difficulty on the pertinent crossings.
And now I can post it and finally be rid of it. :-)
Across Lite file in 5..4..3..
Click to solve.