You should try Desmiit, I have these in green and in white, I think you'll like them.
https://www.ebay.co.uk/itm/Mens-Low-...mvR6 ODprC8vQ
This seller is in the UK you may find a seller in the USA.
Other Desmiit designs don't have the vented rear design, their swim thongs are good too.
You can tell the post office you are a student and ask if you can collect your mail then address this parcel to the post office.