Bypassing Rear Seat Audio Controls to Use Rear Speakers

I have a '99 Astro LT that I'm converting to a camper van so I've pulled out all the interior trim/panels in the rear. The van came equipped with a rear seat audio control in the panel behind the driver's seat. Since unplugging that unit my rear speakers have stopped working. I've been able to temporarily plug the rear seat audio control unit back into the wiring harness to confirm that's the cause. I'd like to get my rear speakers working again but I don't want to have to use the rear seat audio control unit (which I don't need nor have a space for). At minimum, I'd just like them working with the stock stereo but I'm seriously considering replacing the headunit which seems a bit pointless if all I'll have working is the front speakers.

Is there a way to bypass the rear seat audio control unit without having to run new wiring to the rear speakers? (FYI, I've removed the speakers in the dutch doors completely. I'm just leaving the ones in the rear pillars.)

Any help would be very much appreciated. Thanks in advance.