Man, it takes way longer to fix a mistake than just doing it right the first time. I know, this should not be a surprise, it is always like that.
After 3.5h of work I'm done fixing all mistakes I've made. I also used the -6 rivet as I said in the previous post and I totally get now why Van's just tell people to use the 5 even if that's not the right size. Even being extra careful I had to drill out 2 rivets because they were bending. In the end it turns out all I had to do was to stop using the pneumatic squeezer and rivet using the rivet gun, this way was much easier to get it right.
I was ready to move on to the next steps but honestly I want to wait for my building DVD's to arrive so I can take a look. It does not hurt waiting a few more days and it can potentially save me some money.