Supplementing breast milk with formula occasionally

So my SO and I have our 6yr anniversary coming up in April, I was thinking about having our LO (He will be 10mo old in April and this would be his first night away) spend the night with his grandparents so that way we can enjoy a night to ourselves. I don't respond to the pump very well, so I can't pump enough to have for an over night stay so I was wondering what formula would be the best to supplement with?

I am fully aware that supplementing can reduce supply and plan to pump while he's away...if this even happens. I was just asking if other mom's have done this and what formula they used