Stereo guitar sound from mono source

Hi Guys

I'm in a royal blood style band, heavy rock style drums and bass and I'm trying to find a way to make my bass player's live bass sound more intuitive and wide.

I've got his bass split running into a dedicated bass amp into a 8x10 cabinet and also into my orange TH-30 head into a 4x12 cabinet. All sounds good but I'd really like more width in the monitors when we are recording and gigging, the best I can do at the moment for stereo width is hard panning two different dynamic mics on the guitar cabinet, on different speakers, it's wide but it's not wide enough to sound really engaging.

He sometimes uses a TC electronic flashback delay for the lighter tunes and I'm wondering if there is a away to route it to my stereo 4x12 cabinet so that it delays one half of the signal, thus making a faux double bass guitar effect. I'd then mic both speakers and hard pan, I can do this easily in reaper but I'd love to find a way to do it live, can anyone help please?

Thanks guys