Ion exchange (strong base ...

Ion exchange (strong base anion) can remove F but it is not very selective (even supposedly selective IX media for F is not very selective in the presence of competing anions) and F is on the low end of the affinity line.  Aluminum Oxide media may work depending on the balance of the water chemistry.  With the level of reduction you need either might be an alternative depending on the flow rate and usage.  Another option is RO.  With the level of reduction you need you would not need to treat the entire flow just a portion to lower you overall blended average below the limits (maybe 10 to 20% for safety).  This would result in a smaller RO that otherwise would apply for the flow rate and usage.