By "us" you mean the ambassador and your team? I don't think you can put images on the signature section though. Why not go the usual way of linking your services on the signature space, including your social media etc, and then ask your ambassador to manage the threads?
I mean service.
The moderator from the other section sends me here. Is this one section is wrong for this task?
Yes, you are in right place. You are looking for one type of service and you will pay in Bitcoin, so this is a proper section.
Next what you need to do is to explain what exactly you want from someone who will be named ambassador. It's not very clear what you want to do with the signature, yours or someone's else.
define exactly what you want to achieve, maybe it's not bad to write something more about you and whether you have a specific budget for this task.