Having a "heavy GPP day" and a "light GPP day" is really overthinking things, and makes me want to cry a little.
GPP should just be a little something extra to do on the days you don't lift. It shouldn't be balls-out intense or anything too stressful. Think "fun". Think "playtime". Get out, move around a bit, carry your people, swing your axe (not into the people), hit the hammer.
If you are following ABBH II, I'd double check to see if Chad Waterbury designed rest days for a reason (maybe toss a question in his Locker Room).