Can't send CAN frames with extended id over mavlink

[Aleksw3]

I am attempting to send data on the can bus using mavlink. My current setup is connected through mav serial.
When using the function can_frame_send, found in the v20 dialect of ardupilotmega like so:

con.mav.can_frame_send(target_system=1, target_component=0, bus=0, len=0x8,id=0x1e0be281, data=b'22223333')

I receive a message with an arbitration of 0x281 on the other side, which seems to correspond with the standard format (11-bits) of can arbitration. As i am working with DroneCan I need to be able to transmit messages using extended arbitration (29-bits) .
The function class MAVLink_can_frame_message seems to serialize the mavlink message correctly, but somewhere after that the upper 18 arbitration gets lost. Is there something in the code blocking me, or is there a setting I need to change somewhere?