A.Assign more than one managed server to a physical hardware that allows better CPU  utilization
B.Assign more than one application to one managed server to better utilize threads within a single JVM process
C.Assign the same application to more than one managed server to load balance requests  between servers
D.Assign the same heap size to the managed server across the cluster for easier control of  memory footprint  
E.Create a virtualized environment with hypervisor for an easier solution

A.Combine all applications into a single one.
B.Define global roles on the WebLogic Domain level.
C.Use Ms Active Directory to keep the roles there. 
D.Use Oracle Identity and Access Management solution to simplify the management.
E.Keep role mapping in the external WebLogic Role Mapped developed for that solution.