Your research sounds pretty solid. It's a tough one. I would add the following-
- I think the Cayman Aggressor is a good way to dive there, even if they can't make the crossing. It may actually get you slightly better diving on Little Cayman than land based, as they seemed to spend more time in Jackson Bight, which I think is even better than Bloody Bay where the day ops tend to concentrate. But I don't think it is as much "the way to go" like I would say for Belize. And while LC diving is good, I think diving on GC can be as good, as long as you can get to the right sites.
While there's not really a Cocoview on Cayman, there are a couple places you can do nearly as well from land there with a little more effort. Sunset House is the most similar to CCV, sort of - but it's strictly west side diving, south side if you're lucky, and IMO the shore diving there was beat long ago.
Compass Point on the East End you can get 2x2-tankers a day and 2 night dives, but for additional night dives you'd have to drive back to the west end of the island and find an op going out that night or a place to shore dive, and it's really not all that practical. (Especially since you'd be going against the whole routine at Ocean Frontiers, where they clean and lock up your gear for the night, and put it back on the boat the next morning.) Maybe not necessary to sit in your room every night, there's a restaurant there with a buffet night and I expect it is pretty much a divers hangout every evening (it wasn't really there yet last time we stayed.) They had a couple slideshow type nights when we were there in the past, don't know if that is still the case.
Cobalt Coast is 2 tanks in the morning (boat not necessarily leaving from there), then unlimited shore diving in theory. But it's a swim, and they also get blown out a lot there so you'd have to go to one of the more protected shore sites nearby for the afternoon/evening, using a different shop.
Divetech you may be able to get 3-4 boat dives, and the onsite shore dive at Lighthouse Point is less likely to be blown out. Their boats leave from different places depending where they're going and conditions. Staying at LP itself probably won't make sense costwide for a single, but they work with other accomodations if you're willing to go that route. (Just looked and see they have a new shop at the Holiday Inn on North Sound and I assume their north sound departures leave from there now? Maybe that would work, and you could just pop over to LP for extra shore/night diving which probably wouldn't be too much trouble.)
(Are you actually solo diving, or just solo traveling and planning on an instabuddy? Cayman isn't exactly solo diving friendly, and it's certainly against the stated policy on the CAII. Possibly true on most or all of the Caribbean liveaboards, though what happens in real life may vary.)
- As far as Curacao, where did you stay/dive last time? If you stayed near town and dove more towards the east, doing the west end could be like an entirely different destination.
- St Croix could be worth looking into since there's some amount of shore diving, depending how reports come back on that. Cane Bay?
Personally, I'd try Divetech/Holiday Inn, or Compass Point/Ocean Frontiers. Or consider taking the chance with the weather and doing Cocoview. It's supposed to be the more reliable side of the island as you get into the winter, though the shore dive viz may suck if it's snotty. (But it was April and not snotty when we were there, and viz still sucked.) Or the Roatan Aggressor, which looks like it has space for your week, but I don't know if that would be more or less affected by the weather than terrestrial - they can stay on the calmer side, but weather might make them less likely to do Cayo Cochinos which is supposed to be good.
