Regency: Colored Underdress?

As I mentioned in yesterday's massive braindump post, I'm looking for some evidence of colored underdresses used in Regency. (It was a massively wordy post, so no worries if you didn't see it!) To be more accurate, the question is is they were worn with day dresses.

I've started poking around, but I'm already discouraged because this is one place my library of fashion plates fails me. I know there are a few shown for evening dresses, usually ball dresses, make of very sheer (and often decorated) silks, over colored silk underdresses or petticoats.  But I suspect that these were more common than the fashion plates indicate.

To be honest, Georgette Heyer's descriptions also gave me that belief. It could quite legitimately be related to a difference between English and French fashions. Most plates are French, but the English ones show a distinct difference in styling and favorite elements.

I have some rich rose/watermelon colored linen. I've felt uneasy all along doing an 18th century dress with it, although that's what I think of for linen. It is a gorgeous color for showing through a sheer, though. Being linen I can't think it's appropriate for evening; hence my quest to find evidence of daytime wear. I think my best bet is prints, paintings, or portraits.

So far I've found a couple from pre-Regency times, seeming to show white semi-sheers over pink (yes pink) petticoats, here and here.

Then another two show colored under-skirts of some type, but under opaque gowns: white over pink, and mustard over green.

And finally, one portrait that seems to show a very sheer gown of dark green, over a low bodice lining and skirt.

Anyone else have ideas? If it's an awful idea, do tell me!