I have done a few of these large shipping containers like this.
After working on the first one (and having an engineer working along side me) I learned you have to measure and compensate for the length you are losing each time the vinyl goes down in a valley.
If you just make a decal say 20ft long it will be shorter in length once applied down in the corrugations. So you have to make the decal longer to make it look right once installed.
The height of the decal doesn't change.
You can figure it out by calculating it but the best way we found was to take a pc of 2In Masking tape and apply the tape down from the center
of one ridge into the valley and up to the center of the the next ridge, mark the centers of each ridge on the tape, pull the tape off, stretch it back out straight
and the marks tell you the measurement between each valley, multiply that by the valleys the decal will cover and you have your length.
This method also works on corrugated garage doors.