In that case, I reckon a 2kg to 3kg ham would be more than enough...considering bone is hollow and doesn't weigh a huge amount.

When my grandpa was alive he'd buy my Mum a 4 or 5kg ham every year...and with 5 to 7 people at xmas dinner, bone used for soup and leftover meat for sandwiches, hash/patties and etc, it still lasted at least a week and a half in the fridge, often longer.