Since my last post I dived in that configuration: 12 L Steel, 2x DS4, Eclipse 40, normal single tank adapter (not weighted, therefore configurated like in a post from Mats Edenfeldt:
AGIR Black Bird 36 "custom" ).
My problem is the tight hose routing using DS4. A damaged dry suit inflation tube is due to it. Especially the backup regulator hose is captured between the other hoses while having the wing moderate inflated.
Do other single rig users have the same problems?