A tip for those Chaz - some fellow aircraft modellers have had problems with paint creep under them when used for their intended purpose straight from the roll. If you instead cut a piece off and stretch it gently, then burnish it down well, it does appear to work well. I've only used it once and it worked fine using it that way, but that might have been beginners luck!
Tamiya also now do sheets of the excellent material their rolls of tape are made from. This might even work better on the flat bunker and cab sides - if you make an accurate tracing of the areas & transfer that to the sheet it might be easier to work on, on a flat surface away from the model?
These are the sheets, if your local shop is a Tamiya stockist they should be able toget them I'd have thought...
https://www.scalemodelshop.co.uk/5pc-masking-sheets-plain-tamiya-87130.html
HTH
Keith