DZ has always been eminently doable solo for me. It's better in a group and your lifespan of course increases, but solo is viable. You just have to take it slow and pick your battles and pick your extraction zones carefully. I've been running in the DZ alone since level 8 or so (lvl 25 now), and have managed to extract some good stuff (quickly superceded obviously, but still) and have an awesome time.
It's incredibly tense solo, numerous times I've just hidden and watched rampaging groups of rogues run past me. Naturally you will get ganked on occasion, you're vulnerable alone but it's so worth doing just for a change of pace, a sense of being the lone Wolf up against terrifying odds.