Keeping it contained is a know issue with eurorack, it’s one of the most more-ish kind of synth I know. That being said, you can still create a very small setup as long as you are turbo intentional when planning. Your plan is sound although you may come to need a mixer and they are one of the most compromised and costly type of module so keep it out of the rack for less headache.
Why more modules? The Bohm’s have lots of jacks meant for modulation and clocked signals, it is the greatest benefit of eurorack after being able to assemble your own instrument IMO. The drum can take clock to keep repeats in time but it’s not necessary, I’d go for some modulation modules. I really like the voltage block but there are countless ones.
I just got a case from a guy on etsy which is 60hp and has VESA mount and it may work for you if you’re in the EU. it takes a 4hp power supply on the side.
You can find tons more here.