I know people who've sent overnight domestic via Fedex, ups, usps, up to a pound at a time, and they've been fine.
Does this mean you wont get caught, hell no. International mail, probably likely to be more suspect, tho its not like you'll be shipping from Iraq or something.
Dont send it to your home address.
And as far as having to have a package open, thats **.. ive NEVER had to reopen a package for any of the shipping companies.
If yo'ure concerned about it, pack it really well (vacuum), then mark the tape with a small marker, that way you'll know if it was opened. Dont ship it to your house if u can help it, a business address, or something would be ideal