It's simpler than all that.
With the engine running and the bike stopped:
Press & Hold the Turn Signal Cancel button 5 seconds
Press & Hold the Right Turn Signal Button for 5 seconds
The low beam shuts off.
To turn the Low Beam back on, simply Turn On or Flash the High Beam switch. Note that shutting off and restarting the bike will turn the low beam on again as normal, so you'd have to do this every time.
You can easily pull the tail light bulbs, but that will throw an annoying warning light on the dash. I'd go with the painter's tape for that one.
As for the track day, have fun, be safe, and remember that smooth is always the fastest way around the track. The GT is plenty capable, so it's really your own comfort level that you're exploring here.
'13 Dark Graphite Metallic K16GTLD, 24K miles and counting...
'09 Magnesium Beige Metallic K13GT, 60K miles miles and counting...
'02 Mauve Metallic K12LTC, 106K miles and sold
BMWLT#145, IBA# 366, MOA# 111996, SCMA# 24032
All lower 48 states plus Alaska on the K13GT in two weeks . . .
Some people see the gas tank as half empty. Some see it as half full. All I care is that I know where the next tankful is coming from...