For your information the offsets settings for mixes 1 to 5 in order are +6, -47, -100, +29 and +53.
I think using your calculations that this equates to aggregate settings of +59, +35, +6, -18, -47 and -71.
These give near as makes no difference the six PWM settings that I was looking for.
Also the sequence of the pulses doesn't matter as each of the modes can be set to any of them, but you're correct that if I needed them in order I would have to keep moving between the two switches.
Your transmitter screen and butttons are similar to mine, I've chosen switches E and F which are located on the top LHS of mine.
Whilst setting the mixes I notice that mixes 6 and 7 have 5 step throttle curves, could I have used one of these to create 5 step points?