OK, I decided that since the heater hoses were original so 11 years old anyway, time to replace the assembly, and the other heater hose as well. So I let my mechanic have the job.
He said the connectors at the firewall almost always break even with the correct tool (he hates those special fittings too), he just wants to put new ones in there as well.
He'll also do leak check and diagnosis first, see if there are any other leaks; I couldn't tell if hose was just leaking at the Y connector, or if there was a little crack in that Y fitting. And being 106F here, and that Mrs. Cusser drives this not me - I decided to get it done right.
If it had been similar on my Mazda truck or Frontier trucks that I drive, I would've tried the Dremel route, there was room to make a cut. I'll autopsy the old assembly when my mechanic returns it.