My friends, if you hate pin washes, don't pick a WW1 subject!
This simple technique is what I've been putting all my effort into during the past 3 days.
Well, I've also applied some filters over the tank first! Some browns, dark browns, greys, ochres over individual panels, and voila, there's some very subtle variation and the tone has also changed into something more historically accurate!
Washing the model = countless hours. Washing the flimsies and other loose stuff = about 3 hours. Washing the diorama = 1 hour. Phew!