Stan,
I am not at all a pro but on the topic of opaque colors. I used to use inkjet long ago with great success on both clear and white decal paper. then I went to print some many years later, and several printers later, only to discover the ink was transparent and not opaque. Bummer, virtually worthless in my opinion as most of what I find I want is on a clear back ground. I was excited when I heard people were having success with laser printers printing opaque. So I bought some of the paper and gave it a try and at least with black they came out nice and dark and crisp and most important opaque. Not the best picture but this is what they came out like.
I haven’t used the color ones I made but I assume they too will be opaque. I think the toner (being toner and not ink) is naturally opaque, but do I know. If the color prints as well as the black and as well as the white we see here then I think we are in business.