Rebooting the subject again. This time I got clear structure in the nebolosity. So it should be a better base now to start accumulating sessions.
Stretching prooved difficult as this is not HDR, to keep star colors, not totally burn bright stars, bring nebulosity to show on less-than-good monitors, and generally not overdo processing.
Gear: Olympus E-PL6 with Skywatcher 130PDS 632mm/4.86 and SWCC at f/4.55 on Omegon EQ-300 tracking RA
Capture: 82 lights (/86% keep) × 30s × 2500 ISO, master dark
Site: deep country 26km from Limoges, France
Sky: good (given bortle class 3, usual sqm 21.4)
Processing: DcRaw, Regim 3.4, Fotoxx 12.01+