There're plenty of other realistic options, it's just that the government doesn't want those explored for political reasons and the people advocating for the stadium are incompetent. They've wasted the better part of a decade flogging the dead horse that is Civic instead of coming up with, and advocating for, alternatives.
Woden would have been perfect, but they left it so long that all the space there has being developed over as well, and now they're doing the same in the other town centres. You could build the stadium in any of Belco (probably no room there now either TBF), Gungahlin, or Tuggeranong, and it'd be a significantly better outcome than either Bruce or EPIC, and that's without even considering other parts of the city where you could fit a stadium.
BTW, one of the major reasons you'd build a roof is too attract arena shows and larger concerts, and both of those need to be able to control the light in the venue, building a clear roof completely defeats the purpose of that. Canberra can also get up to and over 40°C during summer, which would make using a stadium with a clear roof very uncomfortable to say the least.