The only time I've seen the .50's in the rear was during a CSAR exercise down at Hurlburt, back when the 55th SOS was flying MH-60G's. The tactics for the mission were to operate in a two-ship with the high bird (with the .50's in the rear) providing cover, and the low bird making the pick up. Now while we still use the same tactics (high bird cover, low bird recovery), I've never seen the .50's mounted in the rear. The main reason is that you don't want to commit either bird to one role. What if the low bird takes a bad hit and has to exfil, what if the roles change? Now you've got that big pile of hardware dorking up you're infil/exfil from the Helo.
With the new external mounts (and depending on the mission/AOR) we can mount a .50 on one side forward for extended range (especially in the sand box) and semi-hard targets, and a GAU-2B on the other side for soft targets and high volume supressive fire. If I remember correctly, the Hurlburt bird with the .50's in the rear had the ammo bins up against the internal aux tanks with the feed chutes going out to the guns. But that's from memory.
Yeah, we still carry the penetrator as standard gear along with a stokes litter and strope. Fast ropes only when missions dictate.
And beleive it or not we occasionally carry the internal hoist, and train with it. Don't ask me why since we almost always use the external hoist. I'll talk to our FE Chief and try to find out for you. It really does take up a lot of space, which is always a problem on the Pavehawk. Bring on the -101!!!!! An H-3 on steroids albeit not a Sikorsky bird.
You know, as far as mounting the ETS (External Tank System), 50's in the rear or the internal hoist, it really comes down to what you want to represent. If your going for realism, then reference my replies. If you're going for something that you have your mind set on, then go for it. That seems to be one of the most time occupying considerations I seem to read about with reference to modeling. That and how accurate is accurate. Personally, I think some folks can go WAY overboard when it comes to realism, but even I like to get it as close to the real deal as possible. But I'll also say "enough is enough" every once in a while.
Good luck and let me know if there's anything else I can help you with.
I'm thinking of posting a bunch of images on photobucket or some other free site. My last contribution to ARC went unanswered and unposted.