A very mobile shoemaker?

I still haven't been able to find much information on my ancestor David Horn(e). I know he was born in Makerston, Roxburghshire in 1793. He appears on the 1841 census in Edinburgh. He's probably dead by 1851. But other than his baptism record, the 1841 census record, and the baptism records for two daughters (Isabella and Agnes), I can't find anything. This has led to quite a few questions and a lot of frustration.

I cannot find a record for David's marriage to Isabella. The only record that I could find for a David Horn(e) at around the right time was for a shoemaker named David Horne who married a woman named Janet Wilson in 1822 in Glasgow. The occupation is right, the date is plausible, and Janet's maiden name also fits into the picture (David's eldest son is James Wilson Horne; I'd assumed the "Wilson" was from David's mother, Agnes Wilson, but perhaps there's another explanation here...). Also, if David was married to Janet before he was married to Isabella, it might help explain why there is a six-year gap between James and his next younger sister (the subsequent children are all separated by three or fewer years). James Wilson Horne's death registration does state that his mother was named Isabella... but James may not have remembered his real mother, and the person who registered the death probably never would have met Isabella or known the real story. So I'm thinking Janet could be a real possibility...

... except for the Glasgow bit. It seems odd to me that a shoemaker would move around that much. From Makerston to Glasgow to Edinburgh? A soldier or a merchant or a seaman... okay. But a shoemaker?