It's not like your welding down the side of your car or something it's just the exhaust underneath if there's anywhere to practice this would be the time... Keep going to there's no holes LOL and the disc Sander is your friend clean it up..
What I did with my 99 dollar Harbor Freight welder and I think it looks awesome! I clean mine all up with mineral spirits after smoothing everything down and took some $5 high heat spray paint and painted it all..