Same answer: load-bearing bars.

Though the cover (I wouldn't call it a door) is distinct from the
oleo, it moves with it.

Alright, so, how do you explain that the colours could be different on a
same type ?
My sources : Bunrindo #61 J2M Raiden page 7 different Raidens, all J2M3 same
subtype with red/blue or red/yellow/blue markings, same problem on page 8
with J2M6.
Regards