Thanks for the tip on PhantomJS. I was mistaken, it's not a listener service to be placed on the web server, it's just a stand-alone executable to run from any machine. You can write a .JS script and pass in command line parameters for URL and filename, and have it go out and save that URL to a file. like so:
system = require(
filename = system.args;
page = require(
and call it like so:
...with some tweaking one may be able to define the captured-portion to only the desired chart element, then call this from our consuming apps that require the saved chart image. Still not ideal, owing to it being an third-party, an .EXE on our app servers, and non-supported...but may be better than using InkScape or commercial screenscapers.