Placing airports on top of Gmax scenery using FSSC

I have been trying to create a massive geothermal power rig out in the middle of the ocean, somewhere off the coast of Hawaii. I made the rig itself using Gmax, and it works great. Its big enough that I can put two 3000 ft runways on it (yeah, its BIG) and in fact, an entire airport.
So I downloaded FSSC and started messing around with it. I can create an airport fine, but I can't seem to get the Gmax model and my airport to get together right.
They'll both show up, but whatever I do with FSSC, I get the airport below the Gmax model. Is there a way to get the airport to basically "float" in the air? I just want it to be a little higher (1 ft) above the level that the Gmax model ends at. And I also want to be able to fly underneath it, as the model is so huge you could fly four or five 747s under it in line-abreast.
How do oil rigs in FS work? I haven't found one I can fly under, but I know you can land on the helipads, and those are above the level of the "ground", which is in this case the ocean.
I'm really stumped, here . . .
So I downloaded FSSC and started messing around with it. I can create an airport fine, but I can't seem to get the Gmax model and my airport to get together right.
They'll both show up, but whatever I do with FSSC, I get the airport below the Gmax model. Is there a way to get the airport to basically "float" in the air? I just want it to be a little higher (1 ft) above the level that the Gmax model ends at. And I also want to be able to fly underneath it, as the model is so huge you could fly four or five 747s under it in line-abreast.
How do oil rigs in FS work? I haven't found one I can fly under, but I know you can land on the helipads, and those are above the level of the "ground", which is in this case the ocean.
I'm really stumped, here . . .
