And the closer you get the "pushing" magnet to the one on the scale the higher the scale goes. For the structures, they would need to support the sum of the structure (with the lower magnet in your experiment, though there are other ways to do it) and the weight of the loaded train "pushing" on the lower magnet). Just like any other track structure. Call it a magnetic bearing, perhaps.

A complaint mentioned in a couple of articles about the Shanghai airport-downtown maglev is the rough ride. Maglev is not an air cushion and has no shock absorbers/dampers; it stays at the designed "altitude" for the current vehicle weight quite rigidly. So the structure has to be very precisely built for it to work reliably and with acceptable (though not, apparently, good) comfort.

I hate Wikipedia as a reference, but they *are* a convenient way to get a basic idea of things and a few external references to start real research with. Maglev: [en.wikipedia.org]