Definitely looks doable. My only issue with one piece body suits, and especially under armor, is that if you need to use the bathroom, you will have to completely de kit to do so. It's though enough in my black widow cosplays, I've never wanted to attempt it with Mercs.
Anyway, pattern wise it looks nice, and using snaps or buttons on the collar would be fine. I've never seen this one used so I don't know how well it fits in the bust, but my go to is the yaya Han pattern from mccalls because it contains multiple cup sizes. If that might be an issue for you, you might want to compare both patterns.