I personally think some Tolbunts have mahogany in them. When my boys are crossed with Gold Laced, the offspring are lighter in lacing than the Tolbunt parents, and when they're crossed with other mahogany carriers, the offspring seem to stay the same darkness. But, who knows, maybe I'm just imagining it.
There's "red" Polish out there but I honestly think they're as "red" as New Hampshires or something. . . I wouldn't count on them for a project, plus, they're hatchery birds, hatchery created. And in that case, as you said, one must build the barn before they paint it.
Buff Laced Polish will indeed also be a long project to get rid of the dominant white. Also, again, most out there are hatchery based, just as most LF any laced color of Polish. They're rare in good form, sadly. I have indeed seen good laced hatchery Polish though. My best laced Polish is a silver laced from Murray Mcmurray. Aside from her white patch on the crest, she's nearly perfect!!
But if I really want to speak my mind - I think we're spending too much time dreaming about fad colors. The colors of Polish we already have now are already in need of work, more breeders, and more population improvement. Good quality Gold Laced and Silver Laced are hard to find, Tolbunts (who are very gorgeous and unique!) are very rare and quite inbred, some very weak, and then there's the Creles who still need improvement, and there's even a few Columbian, Self-Buff, and other odd rare colors out there I'd love to see more of.
Again, I don't mean to sound rude or like a party crasher, I just would love to see more people dedicated to preserving what's already there, and, sadly - slowly going extinct. I myself know first-hand how incredibly exhausting it is to find some non-hatchery based Gold or Silver Laced LF Polish.