This is my EV setup and it works so well form my application. I think I might just copy it for the JBL system.
The automatic quoting is so we can figure out who folks are replying to, since the great minds at EH Publishing deemed this forum software to be "What You Need." (cue the Bernard Hermann music)
There are "short" array frames for all models of VerTec; so short they are scarcely deeper that the box that hangs under them. The caveat is that VerTec subs tend to be deeper than top boxes, which may have implications in the future.
We bought short frames for our 87s, and both regular and short frames for our 89s. Mostly we use the regular frames when we do a "reverse frame hang" to get more upward tilt to the array.
Using the fork hangers you currently own, I'd hang the beam/square tube I mentioned in my first post. Find a local engineer to draw it up and put his stamp on it. I'll try to get some pics of the SteelFlex method this weekend.
Have fun, good luck.
ps. Do not modify the JBL array frames. Period.