I had your same concerns when I retired from APD and moved to my retirement home in Wyoming.
My concern was Weight, Canada, and US Customs.
But, the container was put on a container ship to Seattle, then by rail to Rapid City (closest big town). I was given a tag, and I used my padlock. I was the only one who had a key, and the only tag.
I had lots of guns, ammo, reloading supplies, including a fair quanity of gun powder. Not to mention a supply of lead, two lathes, milling machine and other machiney. Also my 51 Chev flat bed.
I have to admit I was worried, turns out everything went off without a hitch.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071