Hrm. I assume the Fling still bans CCR and has their 100 foot rule for second dives in place, yes? Looks like it would be a great site for a light technical/wreck trip.
It would make for an excellent light tech trip. I designed it that way!
The top three floors are pretty open and are very accessible to recreational divers. The bridge is basically a glorified swim through, and each floor deeper than that gets progressively more enclosed. If you go deeper than 100' in the house, it's getting into run-lines type penetration and if you go toward the stern from the engine room, you certainly want to run lines. Although the giant holes they had to cut to sink it opened it up a bit.
On the bow there is the bosons hold that is semi enclosed but it is just a big-ish triangular shaped room. Between that and the hold there is a small companionway that runs straight down from the deck and has a small hallway leading off to the side. Both the companionway and the hallway dump you into the main hold so not really a navigation challenge, but it is pretty tight if you are into that sort of thing.
When we did the clearance dive, we had scooters to get us around, but had a pretty long checklist of things to do (collect cameras, check depths, video any damage, check the list of the ship, etc). Even with the scooters we had about a 45 minute bottom time, I never got deeper than 120. Total run time was about 70 minutes. We certainly didn't get a chance to explore much, and this could easily be a three dive series to even see the entirety of the ship without doing much penetration.
I know Tom Andersen from Island Divers Galveston (may he Rest In Hawaii) tried to put together a tech trip on the Fling a few years ago and was successful at getting them to go along with it. It was going to be half OC tech and half CCR. He wanted to keep things simple with gas mixes and dive planning so we would be invited back. The OC divers had a different outlook and were taking it as their one and only time to go, so things got complicated quickly. Tom wisely pulled the plug on the trip. The Artificial Reef Program has been running tech dives off the Fling for the past 4 years on our research cruises, with both Tom and myself on CCR at some point or another. Since we have demonstrated that we are not complete morons in the water, I think they are more open to a tech trip than in the past, but a mixed trip (non-deco and deco together) probably won't ever happen. If we can get a group together, they would probably run one. It'll probably also cost twice as much as a regular trip since there will only be half the divers.
There are tons of dive sites that are perfect for light tech out there. I know because I've been doing them for the past 4 years. It's just a matter of getting the divers together to go dive them.
-Chris