Both versions with coalitions are public, if you be a part of a coalition, all other players knows how is on you side. That what i mean with "open rules". One version is only for three players - one is without limit of players, but all other players knows who is allied with who.
The "no limit" version is good if we play only 30 days.
I think we can make one or two games with the coalitions options and than we must think about it. Coalitions have shared intelligence for all members!
Suggestion:
Maybe we can make exit rule for all kind of contracts in the PL. All kinds of contracts between players can be canceled within a peace period of 48 hours. It means to leave a coalition, cancel a NAP or to kick some out of a coalition!
So no player can be sure, that he will be not to be betrayed in the end. 