Your so cute Ben. I understand your concern. But yea, it's fine to fill holes with a tack method. So long as the hole is say under 1/2" or so. Then you would want to make something to fill that hole, and then weld that thing into the hole.
I said everything here already. Except for the cute thing. I've met him.

167K on a 02 avalanche only has had a water pump and hte intake gaskets done less then 3k ago.