5S 5000mah are 92W. As you don't want (and can't if you're following the rules) to draw a LiPo below 35% of capacity, you'll drain about 50-60W. A standard LiPo charger for 6S does 50W max, meaning even if you went to the edge, it will take a tad over an hour to charge the battery.

There are heavier chargers out there, 100W seems the next series with an affordable pricetag.

But as Gary writes. Balancing the cells is important. It's also mandated in the rules.