Apologies if you actually answered this one but how the **** do you get straight lines when taping up.
I placed little pieces of tape as references every 6 feet or so, which were measured down from the tops, and up from the bottoms of of the cabin side. It is then fairly easy to get a straight line between these by stretching the tape very taut, and laying it down just next to the reference pieces. Lift up the last foot laid down, move along to the next reference point, pull taught and repeat.
When I was happy with the line, some more reference pieces were stuck down below the laid down tape, and the whole process repeated for the next line of tape.
I believe there is a technique where you can do the whole lot in one go by pulling it taught and letting it snap back, but I couldn't get the hang of it.
Obviously it doesn't matter what bits of tape you use fro the reference tape, but the tape proper should be a plastic 3M tape, both to cope with the streching, and to prevent paint creep. Even then I found it needed me to run along the whole length of the edge with my thumb nail to get good adhesion.
Hope this helps.