Get a bigger case if you can afford it. I wouldn't ditch ErbeVerb as it's a really nice reverb.
You can take a Eurorack level audio signal and patch it directly to your Mackie. But the Mackie has to be able to handle the output level. That will depend on the specs of the Mackie input. You may also have to worry about DC voltage leaking into your audio chain and eating up headroom (you can't hear DC and also it's not good for your speakers). Take the output of one of your oscillators and patch it directly into a Mackie input. Make sure the gain on the Mackie is all the way down. A sine wave is great for this. Can you bring up the level of the Mackie to unity without distorting the sine wave?
If you go with a larger case, severa Eurorack to line level modules are available and might be worth the investment, especially if you're using outboard effects that might have an issue with Eurorack level audio.
Also, the Batumi has a Poti 3HP expander for around $60US. It's worth it as it gives you control of features that are only accessible by moving jumpers on the back of the Batumi.
I'd also look into something like a Befaco dual attenuverting module with offsets, a logic module, and something that does sample & hold + noise. You'll get a lot more out of this rig. I think the Disting can do these features, so you might want to try them out and research their potential within your own rig before buying them.
$0.02.