I'm not saying it's ideal, but worst case scenario. In my cave class we did a simulated BC failure and I clipped one of my tanks off on the line and came out fine. Lost redundancy on the tank, and it's not ideal, but for the few times I ever dive with a wetsuit I couldn't justify the dual bladder wing. With a drysuit it's much easier. If I was diving mostly wet, then I'd consider the dual bladder. Total BC failure is rare though and you can hold some air somewhere in most bc's when they fail.
I do mostly wrecks and one of the things we've done for our scooters is custom sew lift bags that strap along the side of the scooters. If I was diving wet in a cave, I'd just carry one of those and could strap it to a tank or under the nomad. Would get me enough lift to come out. Not fun, but diving dry seems to be the easiest solution for me...
I have my students simulate a wing failure. Even then there's no crawling. It's more like hopping.