Change AV Icon using MAVLink message

I am working on a simulator system that interacts with MP through the MAVLink protocol. We have things mostly working now, but one nit we have is that the default Icon shows up as a helicopter. We would like to be able to choose a quad or fixed wing icon depending on what type of aircraft the user chooses to use in our simulation. Is there a way to configure the icon that is used in MP using a MAVLink message? If not, then is there a way to do this manually?

mp uses the aptype from the heartbeat message to determine the icon. please update your heartbeat message and mp will reflect a different icon.

have you looked into using sitl?