I've weighed about a dozen fresh dall sheep skulls, meat trimmed, but brain in. The heaviest was 22lbs, lightest was 14. I'd say average was around 18-19lbs.
My experience is most BHS are not as big as people think. The giants have really heavy skulls like 30lb skulls, but most are 20 if that, and are not any bigger than many dall rams shot each year. They are a little bigger body wise than dalls, but not much. Most boned out sheep have weighed between 65-75lbs depending on shrinkage/drying and other loss and eating a little of it. The most meat I've got of a ram was 84lbs of boned out meat.
I've packed a few bone in quarters, the last two rams actually. The total bone weight was ~5lbs for all front and rear leg bones. They are not big animals and have light bones.
Capes on sheep, if dry and properly fleshed don't weigh much, 3-4 lbs at most a LS cape is about 8-10lbs. you can easily trim off a pound of meat off most capes.