RE: 65 and rising
You could, but you would have to go for the 'most saintly' range of driving.
But it is better that you do not get to high or low of the battery. Better to just stick in the middle, for battery longevity. Although rented, it does still make a difference because you'll spend less time with a >90% capable battery if you flog it.
In winter, I have been charging up fully out of necessity. Plug in at bedtime and forget til morning.
In summer last, I used to oscillate between 25% and 75% for my 45mile commute. I could do two on one charge, but that's poor for the battery, and also might cause problems if you happen to have a necessary diversion to get kids/shopping/roadworks/etc..
I'd plug in for 4 hrs once back home and simply unplug later in the evening at 75%. That way you can keep the battery in its 'most cosy' range of charge. Maybe give it an overnight to 100% once a week for battery maintenance purposes, usually on Thurs night so that once home on Friday I have a 50% charged car over the weekend. Nice for the battery SOC, and enough to do any 'emergency' runs anywhere.