A couple thoughts on this...
For attaching inside a little enclosure like that, having a plywood backing is best. Even the best double-sided tapes seem to eventually fail - especially when they get hot. It may take 2-3 years but even that's too soon.
There is one option -
these velcro straps with the hole in the middle specifically for screwing the velcro to the back board then secure the device... I can't see enough from the picture but the ones I use have a metal grommet that makes it pretty secure.
Another option kinda touched on -
these stick on cable tie mounts - they are self adhesive but that only lasts so long - they can also take a screw right into the middle to the backboard then they'll never come off. I use these under desks sometimes for cleaning up cords and as long as you use the screw they'll never let loose.
*Edit - as I read below I saw these posted already along later with the tip about the screw.
I've also used that
water heater strapping tape from home depot in a pinch - just cut to length and put a screw tight enough on either side to keep devices in the right place.
The Channel Vision bracket is great for adapting regular devices to SMC - I guess it would work OK for just screwing it to a back board using those holes that are intended for push pins.
I've tried industrial velcro a few times - if there's no real tension and the surface is clean I've seen it break the device before letting go; but other surfaces or those with even a little tension from wires pulling, and over time they'll definitely come loose; again - may take a year or two, but that's still too soon.
I wouldn't go near command strips for an application like this - twisting wires into a box can easily create pull in areas you wouldn't expect - I do these types of boxes all the time with power injectors and I don't deal with anything that isn't a solid physical attachment; I don't ever rely on anything adhesive - and I never lock myself into something that can't be pulled out and maintained.
Cable Lacing is regaining popularity. Especially in data center environments or other sensitive places where people are tired of the jagged edges of cable ties and can't take on the bulk of velcro. I did some radio upgrades for a large wireless carrier recently (big red logo) - no zip ties allowed - the lacing was an art form in how the wires were stacked and kept in perfect placement then put all together inside the racks - I had to learn a couple new tricks for that - but having used it a handful of times now it's my preferred method. It's easier to clean up and never leaves a jagged edge; it's not as easy as it should be though to find lacing string - seems to be specialized supply houses. FYI don't try the junk that cyberguys sells (tried it in a pinch - it's a waste) - it's a flat style that is good for certain applications like looms but not as universal for a lot of the everyday wraps.