How to fix sheet metal holes?

Back to the poor soul asking serious questions!!! lol
I admit I have never used this modern body panel glue but, if welding I not on the plate and whatever, can person cut up some say 20 Ga sheetmetal (4 x8sheet is like $35 here in T. ) and glue it to the backside of the panel and then simply fill whats left of the hole of GOOD body filler??