A few things come to mind as I have actually built such a rack. One- a much larger case at least 6U and the bigger the better.
Two- you need a decent sequencer. I have great experience with ones like Winter Modular Eloquencer it can let you program sequences for recall later to use as preset templates plus view all 8 trigger and cv tracks on one screen- very handy for live use. You need a good trigger sequencer that cannot be understand. Third- attenuators are key and VCAs with envelopes will be essential for drums and bass. Fourth- effects- some reverb is nice on the kick drum and can spice things up a bit. I have the Jomox module and love it but it does take up a lot of space. For bass, any low tuned VCO works. I get mileage out of the Doepfer basic VCO and Noise Engineering Cursus Iteritas. Feed it through a nice filter for squelchy effects when you crank the resonance and get fat bass! I use Doepfer SEM filter and Doepfer Wasp filter for my bass eurorack filters to great results.