I would love to have the ability to reserve a couple slots in a warehouse for specific resources, similar to the train cars.

I have a supply of 3 different resources I am producing that all dump into a single warehouse which is then filtered using filter inserters into individual warehouses for each resource (3 of them). However if one of the 3 types of resources backs up, it backs up all 3. It would be amazing if it were possible to reserve a couple slots in a warehouse for each resource, allowing the sort warehouse to fill up with the one, but still allow the other 2 resources to pass through and not get blocked. I have limited space here, and without major reconstruction, this is my best option right now. Only option I have come up with to work around this is to use a train car for my sort, but it doesn't have the footprint needed for all the inputs.