Like I aways say when this subject comes up, the ENTIRE car is held together with lap and pinch welds! There isn't one single butt weld on the car from the factory. EVERY single panel, including the floor that we are talking about is held on with lap welds! Why in the world is one more so bad?
The only reason a lap weld would perform any different than the hundred and fifty other ones on the car would be if it was done incorrectly.
Leave about a half inch lap like the rest of the cars lap welds have.