What could they charge you with? There isn't any law against "attempted purchase" of class III controlled substances, just possession.
And I know at least 1 person who had customs seize one shipment while the next shipment to same address went through. I don't think our customs department is particularly any more competent than any of the other branches of our government
So too with this keep in mind that if you give a fake name but your real address then it won't help you in the event of a controlled delivery as they'll just arrest you anyhow. So may as well use real name, at least it won't throw any flags up at the post office that they don't have a person by that name ever receiving mail there before.
I've had dozens of shipments from china (none of them anything illegal - mostly computer parts, electronic stuff, some jewelery, a 3000 year old bronze dragon pried off the door of a temple

) and customs never opened any of the boxes as they reseal them with tape that says "this box was opened by customs" if they do.
And last, peptides are 100% legal, can be imported and even if customs looks at them there isn't any issue and they let the box continue. Same with insulin.