And remember, it really IS allowable to add gas to her tank when it shows 3/4 full.
There is no rule ( yet most of my customers have no clue ) that one must wait until the little float hits the bottom of the tank to add fuel.
If the potential for driving/idling for extended periods is pre-known, then I wouldn't pass up the oportunity to top off just prior.
I know that inner city interstate freeway systems leave little option to just hop off to grab a quick topoff ( in stopped multi-lane traffic between ramps ) so I'd find either; the first station when leaving work, or the last station on the way in to work.
Another option is to change the route home, just a tad, so that you DO go to a station first , THEN get on the freeway at a different on-ramp that you do now.
If in danger of running out in stop-and-go bumper-to-bumper rush hour traffic, try to find opportunities to shut off the idling engine.
aside; This kind of stop-and-go, barely moving ( albeit freeway ) traffic is just the occasion to have my 06 Ford Escape hybrid. When sitting and waiting, the engine doesn't idle at all ( o rpm, battery driven ) so I won't run out just sitting and idling.