Custom Fields support for WooCommerce Deposits

I’m trying out the free version of this plugin before I pay for it, to be sure it’ll do what I need, and so far I only have one issue (but it’s fairly major). My client accepts flat-rate deposits for his products, and using this add-on plugin, it adds the total price for the product add-on to the deposit. So, instead of allowing the customer to pay our flat deposit of of $500, it adds the cost of any add-ons to the deposit amount. Is there a way to have the product add-ons add to the product total, but exclude that from the cart total so it doesn’t add value to the deposit amount? I haven’t been able to find any other questions like this for an answer, and so far neither WooCommerce Deposits nor Advanced Product Fields backend configuration address this.