Benny, I almost always buy my postage online and if I'm prepared the night before I may do a pick-up request and have them pick up the package at my farm house (a free service). This was a last minute thing.
I know USPS has a weight limit of 70 pounds but don't recall reading of a size limit, though I'm sure they must have one. I just tried out at
Postage Price Calculator right now to calculate postage and played around with some numbers. I used a package 74" long x 8" x 8" and had no trouble having it give me a postage amount, so that looks okay.
To reduce the spread of pests and diseases, soil should usually be removed from banana plants, in my opinion. Small plants without a corm are weak and have little stored energy, so that's a different matter. It's best to ship those in soil-less medium, if pests are a potential problem. As I said in my video, I shipped Randy a pup earlier this year and he had it planted two days later and he said it acted like nothing had ever happened. That pup was slightly smaller than those in my video, but had more roots.
When I dug up the Belle today my first attempt was not so good and I seriously damaged a pup so I dug another one for Tony. That plant had some small roots so I cut off all of the leaves and potted it up. That should allow it to grow more roots and the removal of leaves reduces moisture loss until that time.