He's got USACI, DbDrag, and Iasca in his area, plus Real SPL: burp at 30/40/50Hz. And if you don't like burps then bass racing is the thing to do.
I'd save the money on resin, total waste of time for panels that big, even with a lot of matt. Add pieces on the outside of the box where you can. Is the box double baffle as HDC4's are 70#'s each. I would not hang those off a single baffle.
Also plan on more power as 2400watts won't push them very hard.
Will you be at Regionals in Oshkosh next month? Would like to check out your build....I run HDC4's also, solid subs.