Conceptually, as long as you're comfortable that your system will always boot from the primary, you could even consider making your secondary USB drive a clone of the primary. You'd have to ignore the VMFS partition from this drive, assuming you provision one, during normal operation. In this case then if your primary fails to boot then potentially your server may be able to automatically boot from the second.
If it's not a full USB drive failure and, such as you suggest, you encounter a PSOD or similar, then this automatic fail over won't occur of course. You'd still have to manipulate the boot order. For the situation you're describing a secondary clone may do the trick and save you from going through the install process. Just boot to secondary, patch and continue.
Assuming this works then maybe you add a step to your regular system maintenance to ensure the secondary drive is cloned from the primary (or installed and patched from DRAC) on a reasonable schedule.
Still, this approach holds some promise. I'd suggest giving it a try.