Hi @Casey
At the risk of this question turning into a shill where developers start plugging their own shipping modules, I may close this within 7-14 days. Having said that, I think you’ll find the Mageside solution I mention in this post of use: Magento 2 Shipping Problems. It’s what I use right now, allowing you to add rules based on variables. It might take you a hot minute to get your head around it all, but it’ll do the job.