Hi Jazzy,
I am in a kind of similar situation as you are. I recently also had to travel quite a bit for work and worried like hell about my just all bought modular stuff. I was thinking about an Intellijel 7U case (with the option to extend with yet another same case that can be connected with some metal connection plates, optional available/purchasable). But just at the moment I actually almost bought the Intellijel 7U case, for my situation I decided against it...
I bought instead an Elektron A4 (Analogue Four), it's nice small and handy and fits in my hand luggage. So I don't have to worry which modules I put into a casing that most likely is going to be too small soon enough anyway. So opted for the A4 when I am abroad and I play with my modular whenever I am at home. Might be not what you wanted to hear but I had too much "headache" regarding deciding which case would be good and big enough but is still comfortable to travel with, etcetera. I admit it might not be everybody's choice of "solving this", but for me this worked out great.
Your Digitakt, if I remember well, is even a bit smaller than the A4, so there should be even more space left in your suitcase!
Good luck with the projects abroad and kind regards, Garfield Modular.
For review reports of Eurorack modules, please refer to https://garfieldmodular.net/ for PDF formatted downloads