In order to determine the panel size, you should first-off have laod calculations for the mobile home. This dictates the service capacity required, although you can increase to amperage, with the utility co. blessings. IF you have a circuit quantity problem, you can install a sub-panel to gain additional branch space.
A 200 amp main (or 225 amp MLO) panel provides 40 or 42 circuits, maximum, as mandated by the NEC.
It seems unusual that you could have 40+ circuits in a mobile home. Is the heat electric??, along with the water heater, dryer, etc??
You can find a listing of the required circuits in the current NEC that is in force in your area
John
