@barksten From my perspective, Elements (and Rings) really unlock a ton of potential when you feed them live sounds. If I were you I wouldn’t order all at once but an Elements and an Ears (https://www.thonk.co.uk/shop/ears-special/) to start with. Get a Piezo and solder it to a cable for the external input of ears. Then some sort of LFO or envelope generator - I don’t have a stages but it looks great for the job, but maybe you should look at Tides, the Befaco Rampage or Makenoise Maths as well. All 3 do awesome superslow modulation.
We just have a plain attennuator (Thonk AT-AT-AT or Dreadbox Attenuator or similar) between our Audio Interface (RME) and the modular, so unless you need the headphone out you could use an attenuator, thus saving some space and instead add a multiple (Dreadbox WL Multiple or similar) - you’ll most probably need one to try all the nice modulation capabilities!
Last thing I’d consider would be to leave some space or get a 2 row rack from the get go once your hooked you’ll want to try out more crazy stuff
All just suggestions of course!