If you have a smart charger, charge the battery every chance you get. Batteries love shallow cycles. But since the site lists charge time as "overnight," I'm guessing it's not a smart charger. What's the capacity of the battery, and what's the current output of the charger?
If you have any electrical skills, you could get a smart charger from a place like an RC hobby store and wire it up. It should be able to fully charge the battery in 1-3 hours.
You can leave it plugged in all summer with a smart charger. I'm not sure that your current schedule is better than leaving it on the shelf until next winter.