Well Ian, I'm thoroughly impressed, both in speed of delivery and result!
I had tried a cyclic method but didn't have a good starting point, which lead to repeats quite quickly. I think I was majorly missing the bigger picture.
FYI - I stumbled upon this site after doing some searching regarding linear programming and the Google sheets linear optimization add-in. From that search I found your 5.1 spreadsheet, which led me to a spreadsheet Richard had put together which was posted on this site... and then lo and behold you are the moderator of this site!
Thank you so much for your help... I knew it was possible... All my friends who tried to help me figure this out will be thoroughly impressed as well
Take care,