Mounting hardware

As an expedient, I've opted to use a pair of NUcs to serve
my (redundant) RDBMS in this project.  This saves me the
trouble of porting the RDBMS to my RTOS, in the short term.
But, the RDBMS still has to "look" like the rest of the objects
in my system, operate under the same constraints, ACLs, etc.
So, I have a (hardware/software) module that sits between
the OTS RDBMS and my system that acts as a protocol converter.
The module is housed in a 2G junction box (more than twice as
large as needed).  My hope was to mount the NUC on the exterior
of the box -- better for cooling, power handling, etc.
(everything inside the box is PoE powered; the NUC's power
demands exceed what I want to deliver over the wire so
I can power them from the mains).
The standard cover plate for a 2G box is, unfortunately,
virtually identical in size to the NUC's footprint.  Good
in that the NUC will fit within the envelope prescribed
by the Jbox.  Bad, because mounting the NUC to the cover
makes the mounting holes for the COVER (to the Jbox)
inaccessible!
The NUC has a pair of mounting holes on the underside
(as usual, my phone photography sucks) visible to the
left and right of the "Intel" label.
<https://mega.nz/file/kjZiVI6a#nhoyBNC2umX-2KdQJW6Uf5NjVC3R3Tz1KIlLea-92i0>
The (four) 2G cover plate's mounting holes are at the top and
bottom of the plate.
<https://mega.nz/file/MnolgACA#UlmLJW0aBJ9QVunfG7a4wNXGM3JasTC6zCU7K-ryw-U>
So, the cover plate would be secured to the Jbox -- after installing
the "protocol converter" inside.  Then, the NUC needs to somehow
be attached (and removable).  The mounting holes are obviously not
going to receive fasteners (screws) THROUGH the cover plate.
Velcro and similar ideas don't look like they will work, long term.
Something with a more mechanical attachment seems in order.  Maybe
something that can be fastened to the NUC (using the mentioned holes)
AND a counterpart to the cover late (the inside of which would be
accessible when the plate is removed).
Any "off the shelf" ideas?
Note that something that grasps the body of the NUC is probably not going
to work as there is little clearance between this and other similarly
cited devices.  Plus, access to the various connectors on the NUC.
So, it seems like behind (under) the NUC is the only real solution.
Maybe a bracket on the NUC and a complementary receiver on the wall plate?
The wall plate is hidden while the NUC is mounted so this should be OK...