Mate, id say make sure your back is fully recovered before making yourself ill. You're young and healthy. Give your body a chance to heal fully before starting up again.
I know it's tough, and i know it's easy advice to give out while im sitting here without a back injury, but it's just not worth taking the chance over.
I don't know what else to say. You're a clever guy and you could train light and see how you go, but as you say, it's not what you're used to and the likelihood you might inadvertently overdo it will always be there.
Anything else the docs can do? Have you thought of acupuncture? I wish there was a magic lotion Gaz, that would make it all go away.