Carrier cutoff time in planning Parcel shipments

We are using Kewill with OTM for Parcel rating. We have some High priority orders which directly comein from EBS into OTM and an agent plans the order on creation. We want to place a restriction in planning that orders shouldn't plan Fedex, Ground after 3PM. We use same carrier code for Fedex Parcel Ground and Parcel Air. Also both Fedex and UPS share same GND rate service. So we can't apply 'No Fedex' Service Provider Profile constraint on the order as this will stop Fedex Air planning. Similarly we cant apply No GND rate service constraint as this will