every service, temporary or permanent must have a service that is approved for service entry. A load center is not approved for service entry as there is no place to ground, there is no barrier of the incomming service conductors and ther is no disconnecting means. You can use a combo panel or a fused switch rated and equiped for service entry. and load center.
A bit of trivia for switches. Any switch that is approved for service entry must have a no coin operated interlock. IE you need a tool to open the door if it is switched on.