"Celts were an odd bunch if they carried about smithing hammers, tongs, buckets and an anvil on their person around all the time just for the fun of it"
Smaller, lighter anvils than you're thinking. Other than that, nothing that can't be easily transported. It wasn't done for fun, but they did carry their equipment around so that weapons could be repaired while on military campaign, and blacksmiths absolutely did carry their hammers around with them.
As far as the fish/meat being a "hunch", I've got over 25 years of cooking experience backing the opinion part of it up, but considering that even in modern grocery stores, the fish section is always physically separated from the butcher section, I'd say keeping raw fish away from raw meat is pretty well established as a common knowledge/common sense thing. If you feel you need specific examples, though, they won't be hard to find. I'm fairly confident their are butchering and smoking forums on the internet, so it's just a matter of asking around, or of going physically to a butcher's shop or an artisanal smoking company.
It's not that I want "substance" for my own diabolical reasons, it's simply a matter of bringing the fish workshop up to a level with the rest of the shops, purely for balancing reasons.