I keep an old breifcase in my office (and one in my car) which is my number one "emergency" bag. It contains the clothing and necessaries for an overnight stay (or -- more likely -- to clean up after I have managed to get myself dirty smile ). No one even notices the case (or the fact that I have two) and if they do they know I am a bit sloppy and often need a change of shirt. Hiding things in plain sight is often the best idea.

It also contains a few of those important items you have discussed, a duplicate of my EDC. I could come out of a shower and have myself back in full kit without any of my previous pocket stuffings. It has been used many times, lots more than the pack setting next to it in the car which is my 72 hour bag.

I wear jeans all the time with walking shoes or hiking boots, so I don't need a "different" set of clothing.