You may be over thinking this.
What are the odds, of all the people driving that route, it will be you being stopped by the cops?
And if you are, what are the odds that the police will want to search your car?
Two 70 year olds?
And if by some very unlikely circumstance you are stopped,
Don't invite or allow any kind of searches if asked, take the ticket without complaint or comment and keep on trucking.
Or avoid the entire thing, stay home and just turn the thermostat up.