ora-4031 and "obj stat memory" component in Shared Pool

My customer has an application which using a lots of "temporary" table. They create so many tables but only operate once.And they are using automatic SGA management,all this cause large memory usage in shared pool, especially the "obj stat memo".
Recently they encountered  the error 4031 , there are still 1G space available in shared pool, so i believe the root cause is too many obj stat fragment .
Verified the issue in the log file as noted below:

At first, i think this "obj stat memory"  subheap can be cleaned up by flush shared pool, but i 'm wrong ; The component is permanent in shared pool.

SQL>  select  * from v$sgastat where name='obj stat memo';

POOL         NAME                            BYTES
------------ -------------------------- ----------
shared pool  obj stat memo                 1454448

SQL> alter system flush shared_pool;

System altered.
SQL> select  * from v$sgastat where name='obj stat memo';

POOL         NAME                            BYTES
------------ -------------------------- ----------
shared pool  obj stat memo                 1454448

After that I  read the metalink note "Bug 5573238  Shared pool memory use / ORA-4031 due to "obj stat memo" in one subpool", oracle support advise to workaround this problem by setting STATISTICS_LEVEL=BASIC or "_object_statistics"=false. But STATISTICS_LEVEL=BASIC will disable many automatic features like ASMM, Automatic statistics gathering;If you set "_object_statistics"=false, then as  _object_statistics control the population of segment stats in the v$segstat andv$segment_statistics views. So setting this to false will result in no data populating these v$views.Both the parameters will require a database restart.
And i have opened a new tar , the oracle support advise as below:


So imbalance between subpool can be fixed , and will reduce the likelihood of  4031 occurrence. But we  can never flush huge memory used by "obj stat memory",i think it's awful .