My local LFS
has an indoor saltwater pond and it is fairly interesting to look down into. I think the key is that you would have to stock fish that swim higher in the water column than the typical "reef" fish that stick right around the reef structure. I don't believe cutting a preformed and attaching a viewing pane would be possible, the water pressure you are speaking of for even a very small pond would likely not be held with this idea.
The costs for the build are really not that absurd though, nor would maintenance require a team of biologists for a modest pond. Here is a link to some plans, granted it is designed for indoor use but it gives you an idea:
Circulation would be handled by a large external pump, start gearing towards swimming pool pumps (3/4hp, 1hp, etc.). Lighting would be free natural sunlight. Base rock for the bulk of any structures. I think the "idea killer" for you though would be the fact that you live in SC. The winters still achieve pretty cold weather there, and heating it to maintain tropical temps would probably cost too much to make it feasible.