You folks seem to have answered the question without realizing it.
First a blacksmith was a smith, an accomplished craftsman. You would not have found an apprentice "released", for to be released, he had become a journeyman, and then a smith. He would've had his own tools at that point, which he had made. IF you did find a masterless journeyman or apprentice, he either absconded, or his master died. Forget somebody impersonating a smith when only a journeyman. The minute they got a tough job like doing a weld, and it didn't work, or failed, their secret would be known, and they'd be run out of town.
Lets consider the trade next. Within the "blacksmith" trade, you have in the 18th century, farriers (horseshoe guys), nailers (they made nails), blacksmiths, and gunsmiths. The first two can work iron, but can they temper iron, and more importantly, can they forge weld? True, farriers were found with the army, not so much the blacksmith, but also the army is its own customer, and has a massive supply train moving with it. The smith with an army probably didn't own his anvil or his forge. There were also blacksmiths who specialized in other things, like chain makers..., but you find them in much more industrialized parts of the country.
Now lets consider logistics. The article on the German itinerant journeymen was interesting, but it was about those trades or crafts where the men go to the location of the work. i.e. Itinerant journeyman masons must go to where the building is being built, but they don't necessarily know how to make bricks..., in Europe a brickmaker did that. The raw materials are on site when they arrive.
When it comes to blacksmithing, you need coal or charcoal, a bellows, tools, iron, and..., an anvil. THAT is huge undertaking in a country with very few roads capable of supporting wagon traffic, AND you also need..., customers. It's a rather daunting and expensive task to move even a basic 18th century blacksmtih operation from town to town by wagon hoping the town doesn't already have a smith, and hoping to find enough customers to make the trip there profitable, with enough left over to pay for the trip to the next town. And don't be fooled by stump anvils and such..., if you were going to do this, you would need a full sized, proper anvil..., for you have no idea what specific skills you will need when you go from job to job, town to town. One man needs hinges, another needs some chain, another needs a fire spit, etc etc. Now add to that the fact the higher populated colonies are also those whose wagon roads cannot be traveled for 6 months of the year due to weather, and you have a very troublesome task...., but the permanent blacksmith..., the work comes to him.
So what we find is that permanent blacksmiths might have a shop less than a week's ride from the frontier, but not on the frontier..., for the smith needs a good many customers to keep him in business, plus raw material support, and the first rule of business is ..., location, location, location . Which is why you can find lots of records of individuals arriving in a town, and setting up a permanent shop, or the local rich guy or guys hire a smith to come to town to set up a permanent shop.
In the 19th century, you may find such a fellow, when the availability of anvils and the much wider use of coal instead of charcoal occurs, but I doubt it in the 18th cenury, for the reasons explained above.
Now you do find itinerant copper and tin workers..., tinkers, and coppersmiths, but remember too they most often repaired items, as copper and tin is much more fragile than wrought iron. Their logistics was much much simpler too, for the temps needed to use solder can be found in a basic fire.
LD