Long story short:
My wife has severe allergies and the doctor recommended that we cover our mattress with a dust mite cover. When we found the cover it was billed as a bed-bug cover and in fine print it also is an allergen blocker (dust mites). This may explain why it was marked down twice - I mean who wants to be seen in line at the store buying a bed bug cover. As we were putting it on the mattress, I remarked that the fabric reminded me of some of the fabrics I was looking at for a winter bivy sack.
Guess what I got for x-mas - a bed bug cover - marked down to $10. I quickly replaced the top with a breathable fabric, added a spin drift protector and tucked the corners a bit at the foot end. I'll let ya know how it works next week.
Edit to add - Thanks for the breathable top fabric - Dave Miles
With 2 pads and a -30 F bag - no mods yet
Corners tucked, zipper added, breathable top fabric added
spin drift collar deployed