I've been doing some reps on my left with my wrist bent back to relieve the weight pressure on my forearm. I know it's not approved and I can feel the loss of stability...

Not only is bending your wrist back "not approved," it's actually dangerous on the tendons in the wrist, which is why it's not approved. Over time (and that time will come quicker as you go up in weight), you can damage your wrist.

If you must use wrist guards to do the strength work, use wrist guards. But try to limit their use as you won't toughen up that area by babying them (like you said you're doing the first couple without them). That initial pain typically goes away in a couple of weeks to a month.