Hi. I agree. My suggestion was to have a beacon of light above a friend (maybe different colours for different friends). You would then also see them coming towards you.
Riding in a group workout when everyone is in the exact same jersey in a blob of 80 riders it is impossible to get an idea of where your buddy is. I think a beacon of light above them would be a great idea. They already do a similar thing with the group leader (they get a crown icon above them) which works great.