Hey dudelove
yes, Dual Lock and velcro are not meant to be paired up. Use Dual Lock only with other Dual Lock (and preferably use different sizes, eg 400 with 250).
Nice idea with the wood. What i did last time to raise my wah pedal high enough when placed on my board so it'd clear the necessary height of the ridge of the board, so it's input jack would be accessible with a cable from the guitar was this. Dual Lock's sticky back surfaced is slightly raised. Furthermore as Dual Lock is plastic, when joined together it adds almost 3/4 of a cm or more to the pedal. I just took 2 strips of Dual Lock and joined them together; the adhesive end of one was stuck to the wah, and for the other adhesive side i stuck on the adhesive side of a standard velcro hook tape. Likewise you could probably repeat this enough times to raise the height till you get what you need (if you want to avoid using glue on wood, for example).