I don't know anything about "inlines" - but, I have seen plenty of standard side locks - both percussion and flint - that the ramrods extended beyond the end of the muzzle - and they were the original rods. I've built a number of ML rifles/smoothbores over the years and my rods all extend beyond the muzzle. I would rather have a couple of extra inches to use when seating a RB - especially after firing a number of rounds - and I always wet patch between rounds. The tip of the rod is below the bore line so it should not cause a problem.
Yea - some may think it looks like H _ _ l, but as Louis Sullivan said, "Form follows function".
When I make a stock, I always try to bore the ramrod hole as deep as possible but there can sometimes be an interference with the front lock bolt depending on the boring job and the components used. On my underhammer, because of the nature of the beast and the location of the nipple a ramrod that doesn't extend beyond the muzzle would not be long enough to get a good grip on. No, it might not be aesthectically nice, but it was not an uncommon practice.
If a pair of '51 Navies were good enough for Billy Hickok, then a single Navy on my right hip is good enough for me . . . besides . . . I'm probably only half as good as he was anyways. Hiram's Rangers Badge #63