ive made home made ghost ring sights that look like a traditional sight on the barrel. they are a type of peep sight and really improve one ability to shoot better. im sure many shooter can do the same as i did. just solder a small washer to the back of a very traditional looking sight and then brown or blue it.
Your post tickled me, as I also had done the same thing on three different muzzleloaders. My last experiment on a percussion about two months ago, didn't seem quite as easy to adjust, so I ordered one of those fancy Williams peep sites that goes where the original rear site goes. Accuracy did not improve, and it seemed like no matter how tight I tighten the screws, that darn thing would shift. This morning was the final blow, I put my homemade peep site, that sets at the very end of the barrel, back on. This particular rifle is drill for mounting a scope, so I just use the back two scope mounting holes with a homemade peep site made out of stiff banding material and a 3/16 washer brazed on. The whole site is about 3 inches long, and the thing I like is that it sits entirely on the barrel, and being it's a Hawkens design, I was afraid the barrel wouldn't always line up if I put the rear site further back. By making the holes a little oversize in my homemade site, I can get enough sideways shift to adjust for windage.
I've also made peep sites out of a 3/16 washer brazed to a number 10 screw that was screw into the predrilled holes on a Thompson Center. If I remember right it's a number 24 thread and it seemed to work just fine. The problem was no adjustment for windage except by moving the front sight.
Squint