I'm gong to go with the white sashing on this one. I posted my choices on Bonnie Hunter's Quiltville FB Group and got 189 comments to my post...most favored the white.
The hubs preferred no sashing, but understood that without it I'd likely suffer seizures every time I walked into the bedroom, which would result in his having to make the bed each day, and dust and vacuum as I would only be able to function with the lights turned off, so he quickly got on board with the white sashing.
I've spent some time calculating (with actual calculator, pen, paper, tape measure). I've unfolded and measured 8 yards of backing fabric, which (Praise the Lord!) contained an extra 15 inches, which means if I play my cards right I won't have to piece something else into my back, though no long arm quilter in the country would touch this quilt, so I'm now going to have to quilt this monster on my domestic machine with 7" throat space (whoops!).
And soon I shall begin to cut 1.25" strips to begin the process.
Ah'll be bach (spoken in best Ah-nold voice I can muster).