Yeah, the stator coil is a PITA to change, on all of the GL1000, GL1100 and GL1200. The engine must come out. However, the engine comes out fairly easily as the frame rails unbolt and you can drop it out.
The stator was only a problem on the GL1200 though as it was oil-bathed, and there were some problems with the early runs with insulation on the stator windings. Honda offers a lifetime warranty on replacement, and the GL1500 or GL1500 Aspencade replacements (with rectifier & regulator) offers a permanent fix.
I've heard that the original stators on the GL1200 generally last around 50,000 miles without replacement. There's also a GM alternator conversion available, but on a naked Goldwing it might look kinda silly.
Looks like a fun project. I think I have heard that the generator is a real PITA to change though but not sure which model.