It's very unfortunate that the feature does not exist with the Nextbox. I also have an SA8300HD PVR and record every Blue Jays game and set the recording for 5 hours because you never know how long a game will be, like the one in Colorado a few days ago, which took close to 6 hours because of a bad storm. I usually start watching the recording after the game has been in progress for roughly 2 hours, then fast forward through all the commercials, of course. Once the game has settled in, if one team has scored a few runs and the other has not, I start fast forwarding until something interesting happens on the scoreboard. If the Jays are out west, I record the usual 5 hours and watch it the next morning.
If you're going to watch it the next day, why not just watch "Blue Jays in 30". All the main plays and hits it 30 minutes. It's on the morning following the game.