I’ve just spoken to an “expert” lol.
One of my sons is a director of an online clothing company with UK offices and warehousing, as well as third party warehousing and offices world wide. He has implemented and supervised overseas operations for a number of years including large volume sales to the US.
He told me that unfortunately ‘smaller’ companies that do not have import/export departments have made a clear ‘business’ decision that the cost/time and sheer expertise involved is not cost effective. Large volume group shipping rates are essential to keeping an items online cost down to a sellable price tag if you’re selling and shipping for export. A requested shipping address outside of the US would be automatically excluded at their online checkout, and only a US mailing address would allow the order to process to completion.
He mentioned that the only option would be to speak to their “contact dept” directly and ask them to allow an order to be held at the warehouse for self arranged collection by a company such as “Parcel Hero”. There would then be PH’s shipping charge plus 12% duty and 20% UK VAT to add to the garment price.
I know it’s not what you wanted to hear, but online companies do not like to deviate from their ‘automated norms’.