Can I use travel trailer while still coupled to tow vehicle?

Francesca Knowles wrote:

You're probably much younger than I am so not yet subject to wandering mind syndrome, but I recommend that you devise some means of reminding yourself that the trailer's unplugged so as to avoid the dread "driving away with something undone" scenario.

It's an easy thing to overlook/forget, especially if nothing else about the hitchup needs attention.