Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
To be honest it is not true.The RLM rules stated clearly how LW planes had to be painted.There were basic camo patterns for all kind of planes both fighters and bombers( used at hight and day),etc...also the desert one.But the war conditions forced the technical crews to adjust these patterns to the battle field needs.What is more, at the end of war there were huge problems with all in Germant so they had to use what they had.
Thank you for these links.They wll come in handy undoubtedly.
For all kinds of German WW2 aircraft there were prepared camo schemes that clearly stated which colours should be used and how these should be painted.So my answer is yes the RLM did. Of course there were exceptions that might have occured in units.
Is there some examples (photos or color profiles) of late war Bf 109Gs or Bf 109Ks painted with black outline fuselage crosses? I've noticed that some late war Messerschmitts had black outline under wing crosses, but crosses on the fuselage were mostly some variation with white outline. I'm curious if any Bf 109G and Ks wore black outline fuselage crosses as some Fw 190s did.
Ad 1. I haven't heard about the similar RLM order.All German WW2 planes were airbrushed in factories with using of paper masks.Of course during usage aircraft in units there was a need to repair or simply refresh a camo scheme.For some reasons it could be made in a hurry or without masks.That's way some different looking camo scheme appeared.More differences appeared at the war end when there was a lack of everything.There are known Bf109s with numbers painted with an airbrush direct on fuselage without any masks.What is more these were assembled with conponents made in different manufactures that used different paints or different layout of camo spots.
Ad 2. There are two volumes of Ken Merrick's books about LW camo schemes and paintings ( pics below).Also I have the AJ-Press series about LW colours but it is in Polish.And I haven't seen the series in English.Certainly there is a lot of books about the thread.
Another is Yellow 5 of JG53, noted as a late G
Modellers Datafile Part 2 F to K variants by Lynn Ritger.