Powdered formula should really be made with water above 70 deg C to kill any bacteria it contains, the point of the boiled water is not 'just' to help the powder mix or to give LO a nice warm feed, killing bacteria is the priority.
If your LO doesn't mind chilled milk you can make up a bottle (with the hot water) prior to BT, rapid cool and keep chilled (back of fridge). It can also be warmed from chilled (by sitting it in a tub of hot water or using a bottle warmer). There are some night feed machines you can get which keep the made up bottle chilled, then at a time pre-set by you it warms the milk. An expense I wouldn't go to but I'm sure many people find them very useful.