The advice I was given for those feeds:

"Sleep with the bottle next to your body to keep it at the right temperature so you don't even have to get out of bed to sort out a bottle."

I think you are a super-mum for using a microwave! As you say, it's just one bottle a day.

Another alternative would be to have a bottle of cool boiled water next to the bed and some formula next to the bed (like one of those going out bottle things) and just mix it up at 5am. Less waiting. But would the water still be OK like that? I am thinking so but don't know for sure.
sleep WITH the bottle? lmao!! knowing my luck itd spill all in the bed or id roll on it and hurt myself...and ive tried doing the cooled water thing but shes a fussy madam and likes it warm haha