Once you have that stag back at the hut and the head skin removed it is necessary to clean the deer head (i.e. the bone attached to the antlers). You would have cut the deer head at a angle that includes the top of the eye socket as the taxidermist may like to have that measurement when mounting your head. The bone (skull cap) must be cleaned of all meat and other tissue.
Below is a six point sika head being boiled out in a New Zealand bush hut. Apologies to all those people who recognize the hut and have used that pot to cook up a bit of dinner!!!
With smaller sika stags it may be possible to use your lightweight camping stove and balance a pot on top.
This was a small sika stag shot in velvet. Early in the season the more mature sika stags will be in hard antler while the less mature are still in velvet.