OK, so it seems very hard to edit the simulated sensors, but I think I figured that out in the end.
About the unwanted vision position messages:
I've been able to get rid of them by commenting out
vision_sub_ = node_handle_->Subscribe("~/" + model_->GetName() + vision_sub_topic_, &GazeboMavlinkInterface::VisionCallback, this);
Tools/sitl_gazebo/src/gazebo_mavlink_interface.cpp and then compiling by
make posix_sitl_default gazebo
Still this seems a rather silly "solution" to me...
I believe that sending these messages is not the default behavior. I may have provoked it by desperately trying to enable some sort of camera. So if you're having unwanted vision position messages, check if your vehicle's
sdf file contains something like
<plugin name="vision_plugin" filename="libgazebo_vision_plugin.so">
and try commenting it out.
Unfortunately, sdf files and their apparently automatic generation process (especially in case of iris) is a completely different subject... but e.g.
iris_opt_flow.sdf has that section.