#1 - If you have body, clothing, space blanket, clothing, air - space blanket does very little
#2 - Body, clothing, space blanket, air - space blanket reduces maybe 20% of your heat loss
#3 - Body, clothing, air space (I don't know how you'de accomplish this), space blanket, air - the space blanket might reduce your heat loss 40%
#4 - body, clothing, blizzard survival suit that has several layers of air and space blanket - that would provide some real warmth, might be a good alternative to a sleeping bag
This is my opinion based on theory, measurements, looking on the internets but may be contoversial?