Welding & downtube storage

Hello, I ended up with a bike with a hole for downtube storage and it's been a big issue. Caps/doors not an option. I am considering having someone weld it shut, but I wanted to confirm with other impartial folks if that could affect the integrity of the bike frame. Would that pose any risk? My instinct would suggest no since a bike frame doesnt typically have gaping holes, but I am not an expert. The bike frame is aluminum, and it is new. I am aware this would void any warranty. I only would like to know the facts and opinions of professionals