I've started writing a reply and saw that you've found a solution, but here is my suggestion also (since I am already writing it):
You are correct, you do not need to add a [Salesman Code] to your warehouse data..
Here is the example:
'USER' as ACCESS,
upper("USERID") as USERID,
SALESMAN_CODE as REDUCTION_C,
WAREHOUSE_GROUP as REDUCTION_F,
'' as OMIT
And your Section Access table should look like:
Your warehouse table should look like this:
'WH' as WAREHOUSE_GROUP,
And your SalesPeople data load should be just like this:
In the example above each user has an access to his/her own SALESMAN data and also to ALL records in WH table.