Don't hold yourself. Spill your nerd brain in here without any hesitation. Who care if nobody like the idea. Even if you make it as your novel, I don't even hold you with anything, and will congratulate you when it finish and enter the market.
I'm having fun working from an initial idea.
I'll play around with an O'Brian version.
It's 2399. Miles O'Brian is bored. He has everything he ever wanted in life. A loving family, successful children, and a nice posting on Earth at the Academy. He never thought hitting every goal he ever had would result in a life that was just so humdrum. He spent alot of time out in space, getting into all kinds of adventures, the entire time thinking he absolutely hated it. But as he gets older and he's spent the past 25 years or so on Earth... he begins to realize just how much he missed it.
He talked to Keiko about pursuing a posting back on a starship. While she was ready to support Miles in whatever he wanted to do, she did have to remind him that given his rank and experience, they would want to place him in a command role. He did ponder just how much he didn't want to be in that situation. He was ready to drop the idea and just accept his boring, safe life.
His outlook changed a few days later when Molly got in touch with her parents. She was excited to tell her father that she had been promoted to full Commander, and would be assigned to the relatively new Dominion outreach program to help facilitate trade between the Federation and the Dominion. Miles had heard something about this, and something in the back of his mind lit up... he recalled an offhand conversation with an Admiral about how Starfleet was having trouble finding experienced... and reputable... crews for freighters. The cadets all wanted to be on the big exploration ships, nobody wanted to run cargo anymore.
It was perfect. He could get back out in space. He could be close to his kids (Yoshi is also out there, doing Starfleet things.), but a freight run would be nice and safe, and given the informality of Starfleet freight operations and the generally small crews of freighters, he wouldn't have to "play Captain" much. Begrudgingly, Keiko agreed to follow him on another one of his adventures.
Upon transferring and getting his ship, his first stop was familiar... he would be heading to Deep Space 9 before heading into the Gamma Quadrant. When he arrived at DS9, someone must have let the word get out. He was greeted by Kai Kira, Bashir and Ezri. Not only that, he arrived to an uncomfortable amount of fanfare as Grand Nagus Rom and Quark had also made their way to the station to greet their old freind.
As O'Brian was done greeting everyone and ready to move on, Bashir followed him. O'Brian said by again, assuring Julian they would catch up the next time he's around. Bashir laughed, and told Miles he should pay more attention to his cargo manifest. Among various trade goods, O'Brian would be ferrying medical and scientific personnel... led by Bashir.
(that's the origin anyway. No idea what the drama would be, but like, surely once they get the Gamma Quadrant, "O'Brian must be tortured".)