So, I am GMing this AP and I instituted a house rule that seems to be working out really well so far: players get 2 additional skill points per level that can only be spent on diplomacy, intimidate, bluff and sense motive. Given how much social activity is involved in this AP, it only made sense to force my players to take some social skills. It has really helped out the Fighter and Cavalier in the party because it basically allows my low skill point players to socialize without being totally hamstrung with no social skills.