In my previous post I underestimated my storage needs with at least 50%. So, I now estimate to need at least 200 GB for master and another 2 x 200 GB for two backups. Add another 3 x 50 GB for my partner. I designed a backup strategy as follows (orange coloured: to be bought)
So the system hinges on a Macbook Pro with 4 external HDDs and a card reader (and a spare card reader). This allows to have a master collection as well as 2 additional copies, of which one will be located in another suitcase. In addition, one HDD is used as a clone of the MBP, so in case of a drive failure in the laptop the system can be booted from this drive. The whole system will be tested in the field in the months coming up to the trip.