you *could* make that happen easily.
There is the base root volume in cDOT (/) where all junctions usually form.
You would have to set the export-policy on the root volume to something that is writeable by a client.
Mount the root of the cdot filer and create the EMPTY volume call vol. That is your place holder.
Then, when "mounting" a junction in cdot, do something like:
vol mount -volume share_01 -junction-path /vol/share_01
and it should work. I did this in a past job with hundreds of volumes so I can tell you it works.
You just need to make sure your export-policies are set the way you want/need and be sure to limit the root volume export-policy when you are done.