Getting the "flat" query corresponding to a view using nested views?
So I know this doesn't directly answer your question but I think are things to consider that may be of help:
Why do you lose the ability to create Views and would you be able to create a second database to house your Views instead? (Views can reference other databases besides the one they exist in.)
If the previous solution isn't possible, could you use a data synchronization feature like Replication or Availability Groups to copy the SAP database to another database where you would be able to create your Views (either on the same server or another server)?
After getting a better picture from your comments, you can still look into Replication to centralize the data into one database outside of SAP, that your product can work off of. Another feature in SQL Server useful for consolidating multiple sources of data into one destination is SSIS.