Bundled stretches do sound kind of perilous. I did them long ago, but have no way of know what contribution they made to my early gains. If you want to try them, just ease into them, paying close attention to any sensations in you penis. There's a lot of complex anatomy you're twisting with bundled stretches. Maybe start with only half a turn + light tension, then go carefully from there.

What about fulcrum-aided stretches? Those can be useful for more directly targeting specific areas of the tunica.

Think more about incorporating warm-ups. Collagen can be made more pliable at elevated temps. Use a heat level that you can tolerate without discomfort, but as warm as reasonable. Give it a good ten minutes or so.