How to know if my work is worth a paper?
Talk to somebody in Field B! That's the best way. 

Make a contact. To find "the right somebody" to talk to, start by describing your idea very vaguely (so nobody steals your idea) to somebody you know and trust in that field, or who has an interest or connection to it. Tell them you're hoping to publish, and ask if they know anyone in Field B who knows more about the topic or might be willing to talk with you. Invariably, your friend will give you a name or two, and you can do the same with those contacts. Repeat until you find the right person. I've had great success in my university with this approach. 

Perhaps you could find somebody in Field B who would be willing to coauthor with you. They might even have funding to publish in a peer-reviewed journal, though that's a long shot. Publishing in a peer-reviewed journal would probably improve your visibility. 

Good luck! If you do get it published, cone back here and link to it. I'd love to see your idea.