My mid-60's (alright now officially late 60's) eyes have gone to hell in a handbasket. I still haven't transitioned completely to scopes- maybe half of my rifles wear aperture rear sights (some with QD scope attachment capability), the other half are scoped. I still use the peep-sighted rifles in the deer woods as much as the scoped rifles, and have developed a couple of workarounds that allow me to do it sort of efficiently.
I wear contacts, and have for 30 years now. I would hate at this point to go back to glasses full time. In order to read or work up close I slip on a pair of cheap readers, or take the contacts out. In the woods and/or range when shooting an iron sighted gun I put a pair of 1.25x half-frame readers low down on my nose, and slide them up in front of my eyes with my right thumb as I shoulder the rifle. They focus light to clarify the front sight & target at the same time (not perfectly but good enough), and the aperture sort of takes care of itself. I'm certainly no optometrist and can't predict if that'll work for you, but for $10 at the CVS you just might find your solution.
Like you mentioned though it's the bewitching time at first light and dusk that presents the most frustration. My solution for that is a bigger aperture which helps some, but more importantly I don't bust my butt to get in the woods while it's still dark like I did when I was younger. Simple. I found that the extra pancake and sausage with a second (or third) cup of coffee is as satisfying as freezing my nuts off while sitting in the dark.
