Sooo.... Finally decided to go for man... Madana (is it?) after getting some help from Lizzy. The mob seems to be just about the right size, the limit of what I can do. It is slow and has slow attack rate. Are there any pure young / mature spawns though? I don't mind taking on a bigger every now and then, but the spawn I was at had too many of them for the hunting to be eco, defensive costs bumped up to 2%. Probably staying at them tonight as well after which I'll go and take a look at the other suggestions.
Check out Goblin+4a for optimized eco on small Madana. I don't know of any other spots except those still listed on Entropedia, i.e. only one place with small and one with big maturities. The great majority is young-old in the former, provs and dom are rather rare. They gave me a hard time, too, when I came with low lvl equipment. Better have a higher dps weapon with you to do away with them quick. As noted above, your defensive costs on Ark will be a bit higher on average. Good luck!
I was about to explain how dropping the ES armor would lower my eco significantly, but then I did some maths and it seems like it wouldn't be the end of the world; 3.150 dpp instead of 3.185... That's about eight ped per thousand shots... (8.41/261.21, about 3.2%) I need to do some tracking without it and see where it goes. Edit: No. Wait. Those. Numbers seem messed up, need to redo it. Edit2: New dpp would be 3.084. That's about 3.2% lower and should thus yield 3.2% less returns. On the hunt from last night, that would mean roughly 14 PED. Despite the higher defensive costs, it still seems worthwhile.