Keith makes some great points. I think many of these site choices like Marginal, the Wanderers grounds, and maybe even Windsor (depending on what becomes of the DND lands) are far too small.
We are really trying to shoehorn a stadium into place, by using just a field and sidelines stands as a template. There is no allowance for a "landing zone" around the stadium for people, vehicles, service, emergency, etc., an events plaza, gates and concessions, a field house for the team and offices, surface parking or parkade (even with transit, a dedicated amount will be required if only as a requirement for permit) and a practice field, which i've observed at most other stadium facilities across Canada (or US).
Just bing-map the area around McMahon, or Commonwealth in Edmonton, or even little Taylor field in Regina. In each case, the stadium itself (excluding the support grounds and parking) has a functional footprint of approx. 200m x 200m (Commonwealth was almost 300m square!) They have gobs of surface parking, practice fields, adjacent ball diamonds, soccer pitches, fieldhouses, aquatic centres, etc. They are true multi-purpose facilities. At Marginal, if we ever managed approval to fit a small stadium in place, there would be absolutely no room for future expansion.
Having said all that about size, ironically I still feel the most (promising) and likely thing to happen in the near-mid term for Halifax would be an upgrade of Huskies Stadium. This would allow for the Uteck Bowl to stay put, and give us a chance at attracting a CFL franchise, possibly an international calibre athletics event too, which may free up some government funding dollars (Moncton got some for its new Stadium to host the World Jr. Track and Field Championships).
Yes it would be a small, specialized stadium custom built into place, parking is an issue that may need to be addressed and it would never become a multi-function park. But think of Molson Field at McGill as inspiration. As you can see in the comparison photo, they are strikingly similar. The Tower Fitness Centre would need extensive renovation to incorporate the main stands, and the building to the north (is it a rink?) would be realigned slightly into the parking lots beyond and redesigned maybe as a new wing of the "Tower". The west sideline offers room for quite a large grandstand like at McGill. Molson really is an amazing stadium, and has a great intimate feeling.