Hi,
You can check the condition type in PO which you can use to account the landed cost. These condition type can also help you in maintaining vendor if the transport vendor is different This is only possible when you are absolutely sure of the place where you will incurr the cost before executing MIGO. Once you are done with MIGO, you will probably have to use the unplanned delivery cost at the time of MIRO level. In case the material price is maintained as standard , the cost will hit the price difference GL. You should refer a MM consultant as well who will be able to give you some more details on this.
best regds
Subha