Apply custom shipping total during or after order creation via REST API

Creating orders via REST no problem — similar to https://developer.adobe.com/commerce/webapi/rest/tutorials/orders/order-create-order/

Need to modify the shipping total either before (quote) or after (salesorder) and recalculate order totals — also via REST API.

So far the best I can find is to manually recalculate everything and update the salesorder via POST to V1/orders — https://adobe-commerce.redoc.ly/2.4.6-admin/tag/orders#operation/PostV1Orders

Is there no better way to have magento do the recaulculation? or to provide the custom shipping total to the quote somehow before the quote is converted to an order?