An alternative to the Roland part is that one from Alesis:
http://www.alesis.com/products/view/module-mount
Exact same size as the Roland , plastic , but only 15$
The APC-33 clamp is basically identical to the the top portion of the PDS-10, with universal clamp
The Roland VDrum units share the same mounting bolt pattern as VG-99 / VB-99
https://www.vguitarforums.com/smf/index.php?topic=757.msg16671#msg16671
More here
https://www.vguitarforums.com/smf/index.php?topic=1078.msg5480#msg5480
I've got my VG-99 mounted to this one. 1U sliding rack shelf (http://cpc.farnell.com/penn-elcom/r1290-1u/1u-sliding-rack-tray/dp/EN55992)
(https://www.vguitarforums.com/smf/proxy.php?request=http%3A%2F%2Fcpc.farnell.com%2Fproductimages%2Fstandard%2Fen_GB%2F42421376.jpg&hash=e7194dbdc139bd31c7f69996e726b4b55b94b8f9)
(https://scontent.cdninstagram.com/hphotos-xaf1/t51.2885-15/s640x640/sh0.08/e35/11378962_1629209567366061_1042442864_n.jpg)
Had to drill some holes, but my VG is safe and roadready.
That's the best method above and is superior to the official RAD-99 rack mount adapter
I'm still looking for a rad-99. Only want it so it adds to the control panel effect so i can play starship. :-)
When i finally gig again, i think a padded hard case and a stand would work well for a guitarist that enjoys a chair while playing. I don't need to stand and play rock star like i used to.
My VG-99 is a part of my mobile recording rig. That's why I've mounted it in a 6 unit rack with my Motu 8M and a MacMini Server. My other devices are mounted in two 2 unit rack cases. One with an Art S8 2-way splitter and extra 4 channels of headphone amping and the other with a Motu 828 MKIII FireWire and an ADA8000. I also bring my Yamaha 01V96 which is mounted in a SKB popup-rack when the situation calls for some FOH/Monitor mixing. I then stack them in two piles on a K&M 18950 Keyboard table-stand capable of loads up to 175 lbs. The stand leaves the floor area very open to add my FC-300, GP-10, SY-300 and other floor related units without too many obstacles.
Altomusic is (or was?) taking orders for refurbished roland PDS-10 stands with the plate for $99.