If you are sure the paint on the bottom of the deck will hold, and not flake off, you could use heavy-duty doublesided foam-core tape (like 3M brand, not generic stuff unless you know the adhesive is really good), for as much surface area as possible between controller and deck. Both surfaces must be very clean and dry before applying the adhesive to them (if the paint flakes off the adhesive will just pull the paint off and not secure the controller).
There are some good velcro-like fasteners by 3M that can work, too (one is genderless and looks like tiny mushrooms and can hold quite a bit of tension, enough so that too much engaged surface area will not be possible to separate without a great deal of force applied at the correct angle). Again, the surfaces must be very clean and paint secure or the velcro will just come off.
If the controller is thick enough to stick far enough out past the tubes under the deck, you could use a very tight strap around the deck. If it isn't, you'd need to glue or tape something to the controller to increase the thickness enough for this to work--the strap must be able to force the controller to push on the bottom of the deck hard enough you can't slide it around under the strap, or else it can just fall out of the strap under vibration/bumps.