If in the US like you said, you pretty much have to hope that they don't find it, even if ordering a gray area chem. They likely will just seize it in transit if they catch it, but it's the US, we love our overly oppressive policing.
Just an opinion piece, but I feel like the list of easiest and most accessible precursors are PMK ethyl glycidate and helional, and then there are other ones like the one other guy mentioned, believe it's mdp2np, while also further "back" ones like piperonyl alcohol, and piperine. Just depends on how much risk you want to take, and how much work you want to do in order to get to the amine.
For what it is worth, I used to work in one of the private shipping companies, one of the big ones. There is so much shit going through there that at a worker level, no one would be bothered if a whole kilo fell out of a box. It's super busy, super stressful, and the numbers/odds are very much in your favor. We once had a package that just reeked of weed, and we just sent that along because that is someone else's problem, and we don't give a shit.
If safety focused, order your shipment on a tor browser on public internet, while wearing a lot of clothing like a ball cap and sunglasses. Then clean your house of everything illegal, and I mean everything. Dont even have a roach of a joint in there. You'll be fine.