Recording a bunch of drum machines and synths

[terrapinsounds]

I'm currently in the process of recording my next album and I'm quickly running out of inputs. I'm using a Behringer XR-18 as my interface. It has 18 inputs and outputs. However I am running into issues recording my drum tracks; as I prefer to record the main track live, I want to be able to record everything at once. I'm running the gear below:

DSI Tempest
Behringer RD-8
TB-303
Minimoog
Subharmonicon
Bass Station 2
Prophet 6
Prophet 08
Crumar Performer
Moog Sub 37
A couple of modular synths
A modular drum machine

With everything combined I have almost 40 inputs. I was thinking of getting something like an Alesis Multimix or some other rack device with a lot of inputs to submix my drum machines before sending to the interface. However part of me is worried that it won't sound very good and I'll have to redo the take from scratch. Does anyone have any other suggestions? I don't have to have everything all plugged in at the same time but I need more than 18 inputs without upgrading to a massive mixer that I don't have the space for. Thank you all for your input.