SMON "trick" to force cleanup of extent honeycombs/extent fragmentation?

I did this by accident once already by inadvertently rebuilding an index into this tablespace that was too large to fit in the available extents and saw SMON ramp up a TON of parallel processes doing space cleanup.

After SMON was finished I now have lots of continguous extents space, but still lots of fragmentation (made worse as I move index partitions into another tablespace).

The alter tablespace coalesce command doesn't really do too much and doesn't clean up any extents (or if it does , I can't find them) and returns immediately and smon doesn't do anything special.

So now I have 2 situations: - Plenty of contiguous space (for a while) but still lots of fragments that could be cleaned up [potentially].

I *suspect* I could try rebuilding another index into this tablespace that would fail but the problem is I now have lot and lots of free contigous space so finding an index that would fail on a rebuild could be problematic.

I tried creating a segment with storage options but since this is an LMT with autoallocation of extents, it ignores the storage clause of the segment.

Does anyone know a trick (or event) that will force SMON to go aggressive on the space cleanup in an LMT tablespace?

Before SMON went aggressive:
[sample]

TABLESPACE NAME                CONTIGUOUS BYTES
------------------------------ ----------------
EHR_DATA                        5,242,880  (largest new extent poss = 5MB)
EHR_DATA                        5,242,880
EHR_DATA                        5,242,880
EHR_DATA                        5,242,880
EHR_DATA                        5,242,880
EHR_DATA                        3,145,728
EHR_DATA                        3,145,728

AFTER SMON went aggressive:
[sample]

TABLESPACE NAME                CONTIGUOUS BYTES
------------------------------ ----------------
EHR_DATA                        745,013,248
EHR_DATA                        671,088,640
EHR_DATA                        652,214,272
EHR_DATA                        585,105,408
EHR_DATA                        537,919,488
EHR_DATA                        536,870,912
EHR_DATA                        536,870,912