Authorizing a card for more than the Order’s total

I’m trying to set up online ordering for a meat store, where many products are sold by weight. We’ve posted the average price of each product and let the customer know that their total is an estimate and that the final total will vary by weight.

I’ve also built a simple app that will let the shop adjust the prices of the items in the order to match the actual price of each pack when they prepare the order, which will fire off an email alerting the customer of their actual total.

The issue I’m running into is that, if the actual price of the products exceeds the estimate of the order, we cannot settle the charge. I was wondering if Braintree provided anyway to authorize the card for more than the order behind the scenes. For example, if a customer places a $20 order, we authorize the card for $25 to give us a buffer to account for product weight.

I’ve attempted to edit the order’s total via the wc_braintree_before_process_order_$THIS->ID hook, but this didn’t seem to have any effect. I’m completely new to WordPress hooks, so I’m not sure if it’s something I’m doing wrong with setting up the hook or if it just can’t do what I’m trying to do with it.

Thank you for your time.