If anything, I would think duties of Maskarrans would be Mafia-esque, either managing large sums of money or arranging for ways to procure sums of money. Since Maskarrans are all about being hidden, pretending to be anything BUT a Cleric would also be fitting - having the Actor feat would be swell for this if you can get it as a level 1 Human.
Mask priests aren't super-churchy by other Cleric's standards. Quoting a FR wiki:
"The church of Mask is second only to the church of Waukeen (goddess of merchants) in wealth. Members of the clergy can call on untold wealth stolen in the past and hidden away in secret places. Maskarran do not hoard or gloat over their takings like dwarves croon over gold; they actively use it to buy agents, bribe officials, sway agreements, and manipulate folk. Clerics work behind the scenes to achieve mysterious ends. This may take several attempts, perfectly acceptable as long as it does not become too obvious who is behind them."
Put a different way, if a Waukeen cleric cares about where the money goes, the Maskarran cares about how that money is gotten - the sneakier and the more complex the plan involved, the better.