Sample size of one, but I was an ordie and winged AC as an aerial observer on shitters.
I used an original CB LF RAID I in exactly the role you need. Civvies, skivvies, hygiene gear, a laptop and snacks all fit with room to spare if I took the right time packing it.
I had a poncho liner, packable camp hammock and inflatable camp pillow stuffed in a cheap stuff sack in case we had to spend a night in the Hotel Sikorsky. String it up between the fuselage members and you're living in style!
I had ATS upright GP pouches, large i think, on the sides for my more frequently used tools and shwag, a camelback bottle pouch with bottle and cup above one of the GPs, and my issued IFAK with some added booboo stuff and an ATS admin pouch above on the front.
On a less practical, more cool guy note, the velcro patch on the RAID is pretty much perfectly sized for a flight suit nametag or a shoulder size det or TMS patch to give ground side Staff NCOs aneurysms when you go over to Lejeune/mainside Pendleton.
Semper fly, brother!