Ken,
Almost all rivet screw ups can be fixed - as long as you plan on paint. Getting up to the airport and having someone look at your work will be a big help. Just having someone who has done it give you an honest opinion does a lot to help with your confidence. One thing to remember, it is your a$$ that will be up in your plane. If someone sees something that could be a problem, you sure want them to tell you - even if feelings and ego are at risk.
Have fun and get involved with the EAA at an airport near you.