If the new preamps are like the old ones it should be pretty simple to do actually, the old eb stingray and eb Sabre used the same exact preamp and one was two pickups with a 5 way switch. Though I’m pretty sure the newer ones are more complicated.Probably quicker and easier to sell and/or trade the 2021 SR 5H for a 5HH honestly. I don't believe the 5H bodies are routed for another pickup, so that would need to be done, and the wiring involves not just the switch but also the PCB. Then there's getting another pickup that matches the existing pickup correctly. You'd have to score one on reverb or ebay because EBMM doesn't sell pickups.