There’s not an easy way to spend a night away from an EBF baby, to be honest! You’ll either have to give formula or express. Each bottle feed for a breastfed baby should be a max of 120ml but if you’re away for a day and a night that still adds up quite a lot so it depends whether you can build up a stash before you go. Using formula will definitely be easier and won’t make a difference to your supply. What you will need to do either way is to pump as many missed feeds as you can whilst away, for your own comfort and to blocked ducts/mastitis. Also it might be important to maintain supply depending on how old baby is 😊
I’ve gone back to work part time, 2 days a week. I’m the same as you and don’t tend to get much milk from pumping so my baby has formula when I’m at work. I do pump at work, I use the mom cozy one and try and pump twice while I’m away. Just for comfort really. I feed my baby in the morning before I leave and then when I get back in the evening. I’ve not noticed any change in my supply or my babies feeding habits since I d gone back to work. I think if you’re just doing it occasionally it as a one off I don’t think your supply will drop significantly. I’m not an expert and only speaking from my experience though.