Short answer is yes.
You do unless
your alternator has an internal regulator
. The ACR is only to allow you to charge a second battery
that you want to keep isolated from the other battery(ies) when not charging
. Personally I would go with an externally regulated alternator and a regulator that has temperature sensors at the alternator and at the main battery and will allow you to dial back the output of the alternator about 10% from its maximum rating.