It can be done. I don’t want to put myself too much further out on this topic. However it’s quite simple.
The UPISS is looking for other things. They mainly x-ray international stuff even then they can’t do every package. Not enough man power or tools. Certain countries are on a watch list. But interstate. No real issue. If you use your head
If you are in business, and want to do this all the time,
I would think maybe contract with a private courier service. The labs in Oregon courier their own samples, although here we have to keep a chain of custody and the lab has to pick the sample.