Brilliant to read the updates and explanations you've added to this thread, Tamar - oh, to have your super-special mod-powers and be able to edit an OP!
I've had no problem in the past with the middle and final parts of your process, preparing the vector/bitmap graphics and applying them to the bodyshell. I used to do this on 1:1 cars (vinyl cut stuff, mainly), so the process is the same... just in scale! So, I kinda skipped the computery stuff and went straight to the eye-opening part - the work you do prior to the middle and final parts; in particular, the materials and technique to create an accurate template to work with. So, now I know what tapes to use, I think you might be seeing more than the usual sticker-bomb and 'badge-work' I've done in the past - time to try a proper wrapped livery.
I've always wanted to create my own consistent livery for the MANY projects on the go - Sideways Porsche 935/77 & Zakspeed Capri, MR Slotcar McLaren F1GTR, Black Arrow GT3 Italia... maybe even a Koenigsegg, too. Reckon you might have given me the confidence and inspiration to get things going... thanks for sharing your secrets!
And, Colin - thank Tamar... this is going to mean more work for you!