eliminate RS232

But that would preclude having a serial console, at least without additional hardware.

Maybe. Alternatively, consider changing to TTL level 3-wire serial over an RJ connector, and fix the bios issue at the same time. Nearly (if not) all modern RS232 transceivers and UARTs are capable of supporting this. That might introduce less robustness in the signalling (and hence shorter maximum cable lengths) but for 99+% of applications that probably isn't ever going to be an issue. For local admin of headless servers then a short cable is fine, and for remote admin, current server densities virtually dictate a terminal server per rack anyway.