If you put the reflector on the stern pole, I think you're giving up a lot (aside from my general negative view of the comparative visual issues). You'll be about like a small sport fisherman. In my experience, it's amazing how poorly they actually are "seen" in rough conditions. It's better than nothing -- but NOT better than up higher.

Our Lensref is only about 10" (or so) in diameter. When we got it 12 years ago, it was highly rated by Practical Sailor.

I recall some of the bigger tri-lenses are somewhat better -- but have a much bigger profile.