Hello everybody!
armornut, Gamera - thanks a lot for your suggestions, I thought about them while trying to work out my own way. It took me the whole December, but at last here's the update:
First I would like to say that in the model you actually have to reverse the order present in the real thing - I mean normally you have a green vehicle and you put spots of different colours on it. On the model you start with the spots by masking them and then you put the "base" colour last.
To get some coherent results I have created a plan in CorelDraw to have something to hold on to. I actually only had a not so clear YouTube video (this one: https://www.youtube.com/watch?v=NtcquzZydXs) to work with, and it only shows the machine from one side. No other photos of this camo scheme are available, so I used my artistic licence. What I actually did was to take the patterns from one side, reverse them and put them on the other side, with modifications where necessary.
I have also noiced that people painting the camo were very practical - they carefully avoided painting on the highest surfaces, on complicated features and so on.
And so I started by putting on the first colour - black, or in this case actually the dark grey, Humbrol 32:
As you can see the masking is already on, and I have also masked the window seals, let's see how this turns out. I'm mainly using Tamiya tape cut up in 2mm squares. In places I have already painted patches of brown, where this is better to mask before next colour. And the next colour is sand, Humbrol 121:
The masking is already there on the above photos and the next colour is Brown, Humbrol 113:
The final colour took some matching but I have finally settled on Humbrol 149. I don't know why they went with this untypically green colour, but that's just how the video shows it. And finally the thrilling moment - removing the masks... Bada bim, bada boom:
I'm glad to say this didn't turn out so bad - a few touchups here and there will be necessary, but the painting IMO nicely conveys the spirit of the original, so I'm glad.
Now I'll try to concentrate on details and put it all together.
Thanks for looking and have a nice day
Paweł