We're starting work on this. I wanted to give a quick summary of our first version we're planning to get any feedback you have!
We'll add a toggle to let you switch from the normal bulk shipping label printing mode to bulk packing slip mode. In bulk packing slip mode, you'll have a Print Packing Slips instead of Print Shipping Labels.
In this mode, we are thinking that we wouldn't support "Combine orders into the same shipment", at least not to start with. This is the feature that groups orders together to the same shipping address.
In this mode, you can still fulfill by barcode, but you would need to print the shipping label first. We have a new barcode based fulfillment tab coming out very soon. This new fulfillment would display an error if you didn't yet buy a shipping label for the order. If you scan the order on the Orders tab we'd bring up the order and the print label screen. You could also manually fulfill orders also.