If I see the flight crew at the gate before they board and I had my kid on hand when younger would always ask if it was OK to stop by during boarding. Rarely did they ever have an issue and if they did they generally asked to do it on de-boarding when arrived.

As others suggested politely ask the FA working the door with a "no problem if they can't" - generally they will accommodate unless you are a way later boarding group.

I don't quite have the figure for it to pull it off. But for next time maybe I should bring a tux, casually order a Martini - shaken, not stirred and put my wind goggles into the seat back pocket ;-)