There’s been a couple of times when I was about to pull a card out of an Apple II and noticed that the power was still on. With the IIe it’s pretty obvious but while there is a power light on the IIgs, it just doesn’t stand out. A while back for a project I bought a batch of LEDs on wires with a resistor in line and the connections covered in shrink wrap.
I just soldered the wires to 5v and stuck the LED in a vent hole. It wasn’t the tightest fit so I added a tab of silicon. If it should somehow come loose, there’s no bare wire on it.
Not a bad idea.