I looked at terreriums and it seems like the tank would need to be
removed for things to be installed correctly? I'm not even an
amatuer - let alone an expert - so I have no idea if that's the
case or not.

I don't think so.

You guys seem like a pretty knowledgeable group - what would you do
if you had maybe a thousand or two to spend on this project to make
it look presentable - if not really cool looking?

Does the owner like reptiles? That would make a great home for some bearded
dragons! They need UVB light, which shoudn't be a problem. Some kind of
heating from overhead that makes a temperature gradient in the tank.
They're dry/desert animals, so maybe a small fan to move the air.

I would LOVE having something like this....it's hard to ever have a big
enough enclosure to make a good home for a reptile. I keep boa
constrictors, an iguana, a turtle. I would NOT recommend an iguana, though.