Thanks for the reply, I was thinking of using two 4 foot sinks so that it would be easier to ship, but never thought about the consequences of the two lips touching. So, I think I'll go with the 8 foot convertable sink and have the contractor erect the legs rather than buy the ones delta sells and we can probably stiffen them better.
Nige, thanks for the photo of your dark-room. That is about the size and space I'm going to have available. It is always encouraging to see what others have. And yes, there will be plenty of GFI outlets above both the wet and dry side. I'm always running out of electric contacts.
One other thing. I can get a Thomas safe light cheap. Is this space too small for one? I like the brightness of them, but fear I won't be able to tamp it down enough to not interfere. I like the almost daylight brightness against the ceiling.