The one thing which you reported that I tend to question is:
.The results are: Blownout midtones - unprintable even burning at 2X base exposure. The subject roses look good and are quite interesting to me. They are in the area of my intent
The reason that I question that statement is that I have heard of blown out /blocked highlights and I have heard of underexposed shadows but I have never heard of blownout midtones in my life.
If the shadow detail is there and the highlight highlight detail is there then the midtones need to be there as well. Perhaps if one knew which end of the spectrum you feel is missing then a direction might be more readily addressed. The matter of metering this scene is the same as always. Expose for the shadows and develop for the highlights.
Additionally you failed to account for the effects of the red filter on the green foliage. It darkens it as it is the opposite of green. Filters lighten like colors and darken dissimilar (opposite) colors in a print.
.The subject roses look good and are quite interesting to me. They are in the area of my intent.
The red filter lightens the color of the red roses and that is why you got some exposure on the blossoms (I am assuming here) but no printable exposure on the green foliage.