Yep, as far as second jobs, it cannot be anything that competes with USPS, including DHL, UPS, FedEx, On Trac, even Amazon. And USPS will tell you your job with them comes FIRST. Consider this. If you are scheduled to be at your other job, and USPS calls you that morning saying they need you that day, they can discipline you if you don't drop your other job that day and work. You could theoretically just not answer your phone, but even that, after so many times, probably won't fly anymore. USPS expects your job with them to be your highest priority, even above your family. It's unfortunate they treat people this way, because I actually really like the work itself....
Magnolia, I'm guessing you were born in '72 from your username. Me too, and I'm a fellow seamstress as well. Before I started with as an RCA a little over a year ago, I'd had a cloth diaper sewing business for five years (though I'd been sewing clothing for the family for many many years before that). I worked my tushy off too--I got pretty burnt out. I ended up closing my business, because I just couldn't compete for what people are willing to pay. They value cheap over quality. I'm looking forward to getting into sewing for my family again, but haven't because I've got tons of diaper fabric here that I don't know what to do with... So, sorry for the long story, but nice to "meet" someone with possibly a similar background and and current situation.