I had this problem with putting my Boss pedals on my pedalboard and feeling that the adhesive velcro didn't stick well with the rubber on the bottom side of the pedals, so I was trying to find a part that suited well on the pedal and that wasn't too expensive, and found this.
Only drawback is that this base plate doesn't fit on older Boss pedals because of the lower 9V power input jack, so best to first check that on your pedal. The slightly more expensive Soulman Boss Mounting Plate fits older Boss pedals, but otherwise I would recommend this one because of the lower price.