Instead of putting the garage on with the house panel, install a 320 meter base with double lugs use one set of lugs to feed the house and the other to go back into the ground over to the garage and feed a 200 amp main breaker panel, this way you only need 3 conductors to the garage as it is still part of the service entrance conductors and is allowed by 230.40 exception 3.
No disconnect at the house is needed for these conductors as they do not enter the house, and grouping of disconnects is only for each building not each service a common misconception, very common way we do them around here.
Keep in mind that grounding electrodes at the garage will be required just like any service but you don't seperate the neutrals because it is not being fed by a feeder, you just treat it like any service install you just don't have a meter at the garage.
Wayne A. From: N.W.Indiana
Be Fair, Be Safe
Just don't be fairly safe