It would count as one of your 3 FP.
We were just there last week and watched from right next to the FP viewing area. If you want to come 15-20 minutes before the parade and get very good front row seats.... I'd say go for it.
I saw the FP area and started talking to the cast member around 1.5 hours before parade time. So.... they told me that at the end of the FP area (on the left side as you face the castle), they put up a rope from the FP area across the street to where the parade turns and goes through frontierland. I situated myself in the middle of the street where she pointed me and once the rope was put up....viola, front row seats! They were great. But, I was there holding the spot for quite awhile before the parade. It was worth it, I thought.
But, if you don't want to wait and just show up in time.... the FP seats were the only front rows left.... unless you ventured down into Frontierland to see the end of the parade.?