Removable Magnetic Mounting Solution...
Probably the largest complaint I hear from sales reps here is that they don't want to permanently mount the unit to their phones. Neither do they want to have to change out their current case for a case the unit is mounted to (too cumbersome).
I would like to suggest a magnetic mounting solution: A small, unintrusive plate could be mounted on the back of the phone/tablet. A matching plate could be mounted on the back of the spike unit. Neodymium magnets could be used to ensure the plates are small and matching divots could be incorporated into the plates to ensure the plates align the same each time the unit is mounted.
Jason Cardot commented
I have a suggestion for you. Use velcro, that's what we do. It works great!