First - Did you confirm that your Right eye is indeed your 'master eye'? If not - please report back - as there's simple ways to confirm that, like at this link here:
https://www.allaboutvision.com/resources/dominant-eye-test.htm.
Then, if you are right-handed and with a right master eye, then you will reduce eye fatigue, maintain true binocular vision, increase the available 'light' for seeing the sights, maximize situational awareness and improve visual acuity by shooting with your left or 'off' eye open; so that's 5 bonus reasons right there!
What many top competition line shooters (e.g., like 20-times shots offhand @ 200-yards) do is add a 'blinder' or eye shield to their off eye, that flips up out of the way when not shooting - see the Gehman-type eye shield below.
For muzzleloading, here's what I do. I stick an aperture on my master eye, where note on the shooting glasses shown I am
left-handed, so that aperture is on the left lens. My MZL'ding glasses on the bottom and my general rifle/pistol shooting glasses on top, where for line shoots I'll add the blinder/shield. Yes, I'm not prohibiting sight or vision from my off eye, but I'm not closing it either, where the master eye prioritizes my vision simply looking through that aperture, so in effect it essentially takes the off eye out of the equation.
TIP - Acting on some helpful advice from
@ADK Bigfoot, I'm experimenting with repacing the black electrical tape aperture with opaque packing tape, so while it's a not really 'clear'/milky white tape in color, it is less noticeable when not shooting .. but honestly, I never cared a wit if someone said,
"Hey, what's that on/in your eye?", as I'd tell them to just go look at my score versus their own, LOL!
BTW, when not shooting, even with the black tape, it does not block nor interefer with my primary vision, as in normal eyesight I am looking directly through the center of my lens. But for most shooters, when in their shooting stance, their head is not turned all the way forward, but is off at an angle, so if you note ... the aperture is closer to the nose bridge than being in the center of your main vision (when not shooting).
Link = https://www.muzzleloadingforum.com/...our-glasses-so-you-can-see-the-sights.160334/
Eye Shield/Blinder:
Try some of this out, I think it will work for you!
But confirm your master eye 1st!