Here's the video for the positron glitch, with another video
here exposing another method of getting your pikmin into the upper section. Both equally useless however, since to get out of bounds you need an upgrade not available on day 1, plus moving the PG into a position where reds can reach it requires ending the day, plus day 1 automatically ends when you grab either ship part, so clearly 6 days it the absolute minimum now. That trick might be useful in a red-only Pikmin run though, since there are
similar glitches which allow you to take a few of the other parts.
But of course in a TAS, do we aim for real time or game time? Well considering it took around 10 mins extra on day 1 to grow flower pikmin, which move and attack about 50% faster, and we use them for about 30 mins, I'd say it'd still be better in the long run to have a long boring day 1.