I don’t know, I think your analysis here gives far too much credit to Trump and to the majority of his followers. I don’t think he needs to be sending subtle signals (or that most of them would be capable of catching them), for the most part he’s pretty overt about what he wants and what he thinks.
As you point out, there are clearly times when he censors himself for TV even though it’s obvious what he really means, but I don’t think his most racist supporters need his racism to validate theirs.