Regarding the colors carried when the regiment was a regiment of carabiniers, is it worth it to mention that Schirmer conjectures that the regiment may have carried a Leibstandarte and Compagniestandarten? He suggests that the Leibstandarte was white with either the ducal monogram or coat of arms, and the company standard was red with either the ducal monogram or the white horse. I can see that this may have been the case, since the uniforms were modeled on those of the Prussian cuirassiers, and it is plausible that the colors also followed the Prussian cuirassiers' model.
We do note that by the time of the American Revolution, when the regiment had been converted back to dragoons, that they carried a guidon. Reconstructions of the guidon follow the British pattern for dragoon or light dragoon guidons, with a shallow swallowtail and rounded trailing corners.
Best regards, Brad