I don't have a Selene II (nor even know what it's like), so I can't help with specifics. But I just thought I'd mention that I had the same problem, so I know where your wife is coming from. I'm really short-waisted, and with the waist strap of the BC fastened around my waist (obviously
), I couldn't look forward. I had to do a sort of side stroke/side-peer to see ahead of me - that got old really fast.
I tried various approaches (changed hoses/orientation on my first stage, borrowed a buddy's first stage of a different brand, spaced tank away from backplate slightly, etc.) to fix the problem. Spacing the tank slightly further from my back helped (not that I wanted to move my CG upwards, but it was only 3/8"), but what finally really worked was getting an STA that allowed me to move the upper cam band down on the BC.
Now I can put that cam band just below the crown of the tank and I can lift my head normally with no problem (I can just force my head to hit the first stage, but of course that's not bothersome). I happen to typically trim out head heavy/butt light, so moving the tank "down" only helps that.
This does make it slightly harder to reach my tank valve while I'm suited up (in fact I can't do it anyway right now as I'm getting over a shoulder injury), so I'm extra careful to check that my air is on before jumping in, and making sure my buddy is in close proximity. When my shoulder recovers I will re-evaluate (this is with a single tank).
One thing I noticed (and this is build-dependent) is that many people (who happened to be men) offered the option/solution of just adjusting straps and moving my BC down. This is a natural suggestion as I think it would work for just about all men and some women of "boyish" figure. I happen to have a smaller waist compared to hips, so loosening shoulder straps, etc. does nothing to move the rig down. The waist band is not moving down unless I start sawing bones...
I hope you don't mind my replying even though I could not directly answer your question. When I was trying to get my BC to fit I sometimes felt a bit "alone" due to the fact that most (actually, all, at that time) of the dive professionals I was interacting with were male, and so in some cases their suggestions didn't work for my particular build.
It's great being able to see forward when I want to
Blue Sparkle