Shipping still selects smallest box, not cheapest

An ongoing issue with how shipping rates are calculated is that if there's a custom box that the order will fit in, that will be selected even if the shipping charge is higher than using a USPS Flat Rate Box that would also fit. This means that some orders that go to a distant state are charged a much higher rate than if a Flat Rate Box was used. If we removed the custom boxes, then more local customers would get overcharged!

I've raised this issue with support before, but there seemed to be no interest in resolving it. A simple solution is to just display for the customer all the available shipping options and let them pick the one they want.

I had the idea that I could add a second USPS shipping choice, one restricted to local states. I'd then remove the smaller custom boxes from the other choice, which would have the rest of the states. Not a perfect solution, but I think it would work. Imagine my astonishment and annoyance when I found that zones were no longer available for calculated shipping! Worse, the Pickup option, which we use and restricted to local zones, no longer allows zone selection, as this feature is restricted to flat rate and by-weight options. This is a major step backward!

Is there a solution I have not thought of?

I did just now find an ugly workaround. I added a second USPS shipping option without the custom boxes. The customer now sees two identically named shipping options with different prices. 

So - no takers, eh? I do not consider my "ugly workaround" a solution. Squarespace is absolutely wrong in showing the customer only the smallest package, and also wrong in not allowing "store pickup" options to be zone-restricted.

I am having a similar issue with USPS Flat Rate Boxes.  It is not moving up to the next size box, but rather uses 2 smaller boxes.  

Also, not offering Commercial pricing.