Keep in mind that breastfeeding doesn't have to be an all or nothing thing - you can supplement after each feed with a small bottle of formula, which might help relieve your wife's concerns about volume. It's actually a pretty common practice, you just don't hear about it because of all the shaming around formula vs breast milk.

You might find this research study interesting if that sounds risky: https://www.jpeds.com/article/S0022-3476(17)31770-5/fulltext It showed no negative impact to topping up, but readmission rates to the hospital were actually a little lower! Kind of makes sense, considering those babies are getting likely getting more food overall.