Why don't you just turn the mic pre gain down a little? Or ride the gain on the loud parts if necessary?
You need an external limiter if you want to nip the peaks, but it needs to be placed between the mic pre and the ADC so it won't prevent mic overload.
Using a plugin will not help prevent overs since the plugin will be after the ADC.
If you record at a lower level you can use either a plugin or an external pre which ever you find easiest to use.