Have you considered coning the muzzle so you don't need a short starter? I coned my Lyman Great Plains .54 flinter and it's a joy being able to thumb start a ball and go straight to the ramrod to seat the load. No accuracy loss either.
No, When I carry my longrifles I still load from the horn & pouch, I like the tradition of taking all the steps to load even if it takes a lot of extra time.
I'm not sure when they started coning barrels and I don't have anything against it.
Thats the nice part of muzzleloading we can each do our own thing, create tools to enjoy the sport in our own way.
I'm not big on sidelock percussion rifles but no doubt that's a good looking rifle! I've been building, repairing and shooting ML's for 28 years and I strongly advise against coning. In theory, the cone should not have an affect on accuracy but, more often than not, "theory" does not correspond with reality. "Acceptable accuracy" is a matter of personal opinion and as such remains a personal choice which is why I "advise" not "dictate". I have seen coning turn an excellent shooting match-grade ML barrel into junk.
Coning is tapering the muzzle from groove diameter to bore diameter over a linear distance of about 2-3 inches. The problem is, even a few thousandths of variation in the cone itself or in how the PRB hits it on the way out can allow the gas to shove the ball off its normal course. A standard taper or radius crown can be adjusted in such a manner as to change the POI considerably and a coned muzzle is nothing more than a greatly exagerated crown.