I would have thought that you would already have the colours required.
For the ground crew work clothes either the two piece 'Drillichanzug' or one piece 'Arbeitsschutzanzug' came in a raw cotton colour (rohgrau) which varied from almost white to a light canvass colour and also in a more practical black, though a very dark blue/grey looks better on model figures Both could be lined or unlined for summer and winter wear. I have seen plenty of photographs of personnel wearing a combination of the two colours of the two piece outfit, which makes for a bit more interest.
For pilots it is a bit more complicated. Fighter pilots wore a bewildering variety of equipment, often including personal items, particularly leather jackets. Generally bomber or transport crews wore the issued flight suits.
As for colour, again there was much variation. Most common would be a grey/blue material and a brownish colour. A less common material was grey/green in colour. In April 1941 the production of one piece flight suits was halted and two piece combinations (Flieger-Shutzanzug Kombination) became standard shortly thereafter. They came in various forms (summer, winter, heated etc) but look very similar, certainly on a model figure. Late in the war some all leather flying suits were issued to fighter pilots these were in black leather or more rarely brown.
When you have some details I can tell you what would be most likely for your guys
Cheers
Steve
Forgot to say that if you are going tropical the often seen shorts were actually part of the equipment issued for sporting use. The Nazis were keen on sports as we all know!