To get back to the topic for recording optimal levels @PamPurrs . I think you could use a DI box (or a preamp pedal) that connects to your DAI instead. Then you can just use the rumble for your stage volume. That way you don’t have to worry about feedback either since the signal is already processed into your DAI before the amp.
If you want the tone of the rumble preamp then you could use the send/return perhaps and put your DI box in that effect loop or you could mic your cab?