You're getting some good advice. I will caution that people tend to give advice based on their own personal experience with loved ones. I don't know nearly enough to recommend the need for 24/7 help. When you say "grey area" cognitively, that could mean different types and levels of cognitive decline.
Cognitive issues; whether normal aging or a disease process, will be particularly exacerbated with fatigue and a change of routine, so the actual travel can be a particular trigger. So some type of assistance there would be helpful for anyone. If that assistance is a family member companion, they will have the advantage of knowing your relative's normal baseline and will already have a rapport with you and the relative in question.
Good luck with this. It's difficult because you want to help but you also don't want to give the impression that you are forcing your relative to do something, or not do something, they want to do. Agency is important in folks with cognitive issues, even for folks with something like Alzheimer's. Telling a person "No" or trying to fix their perceptions to match your reality can often be a negative trigger. There are particular redirection skills that are far more useful regardless of where a person might be on their journey