[Kazeto]

Actually, you might be able to come back here. What some people don't notice for a long time (yeah, it took me some time to notice that too) is that the oxygen-replenishing algae in caves do spawn over time, so for as long as your starting oxygen capacity is high enough to get anywhere you might very well be able to return.

That being said, when I'm overloaded like that I just fly to the nearest station in that sector, sell all that stuff, and then gather the rest. I never really had a problem with those fleas ... but then again, that might very well be because I mostly use trader ships so it's hard for me to lose a lot of cargo (which I think only happened once to me, all the other times it was just a few units of cargo spilling).