The quick question is: How might it be possible for you to set a particular outfit for a Sim as their default “going to work” outfit, overriding whatever Maxis/EA might think they should wear on the job? The “set suit to” cheat does not cover this problem, as no matter how you set it, the Sim will quickly change into their “working gear” before departing for the day.
The backstory: In creating my Sim neighborhood of Hawkins, Indiana, I naturally wanted to have not only the locations, but also the various characters to act and - at the very least - look as they do in the Netflix Stranger Things series. I figured out how to arbitrarily “promote” Jim Hopper to the rank of Police Chief. I even downloaded a good approximation of his khaki Hawkins Police chief uniform, which he is more than happy to wear as everyday. But when he goes to work, bam! Out pops the default Maxis blue cop outfit. There was an option to download the outfit as a default police gear replacement, but I want OTHER cops in the neighborhood to keep their blues, just like the uniforms in the fictional Hawkins (themselves an homage to the cop uniforms in Jaws). So, can I set a particular outfit as a “work” outfit? Is this what Tom’s Clothing tester might do? Although extremely helpful in other areas, Calidan’s Testing Cheats document just kind of glossed over this topic.

Could something like this work? https://www.modthesims.info/download.php?t=299589
Not quite, but maybe better than work outfits. A lot of people do go to work in casual wear anyway.

This tutorial shows how: https://modthesims.info/showthread.php?t=129052

What I’d like to be able to do is send my sims to work in Casual clothes; The game won’t let me. I should’ve mentioned that the newest EP i have is Seasons, and [horrified gasp from the community] I’m using a Mac. So... ANYTHING involving SimPE is out, to start with. I just wondered if anyone had ever come up with a way to add a work clothing option to the “Plan Outfit” action, or something along those lines...

Turns out, the AL download was a modified one from squinge or somebody, who made the original for the base game. A little digging got me there, and now ALL my sims will go to work in their everyday civvies, which I think will work as long as I can get them to wear what I want as an everyday outfit. So thank you for the info!

What I do is change my Sims clothes after they automatically change into their work clothes. It isn't automatic but using the Insimenator's option to add its Wardrobe option to the Sim's menu, I just click on the Sim and click Wardrobe, Change To... and select whichever clothing category I want them be in. It happens immediately, no clothes changing spin occurs. I can usually get it done while they're walking to the carpool without having to pause the game.

When you're looking for a hack/mod (or have problems with your game), make sure to list your last EP/SP and/or game type (UC, separate discs, collection discs) in the text, to be on the safe side. Just for future reference, because it makes finding stuff a bit easier