my understanding is: bays (think airplane seating,max few days) < steerage (think hostel, you better be friends) < 2nd class quarters (motel, semi-private) < 1st class quarters (hotel, complete privacy, desk space, etc...).
I think of bay quarters as enlisted quarters on modern ships (three high racks in contiguous spaces).
Steerage quarters would be multi-person staterooms with shared heads down the passageway.
"Standard" quarters would be no more than two people per stateroom.
Officer quarters would be single rooms, possibly with their own heads (or a "Jack and Jill" one shared with one other at most).
I'm skeptical about this one, at least for infantry bays. Cramming 30 people with an average mass of 100 kg each in 5 tons leaves 66 kg/person, including seating and life support. That seems like airplane seating rather than triple bunk with a storage locker.
187 pounds with gear seems rather light from what I know of practical infantry, but maybe space travel selects for little people. Either way, I think you can see what I mean? That's still in the ballpark of airliner allowances.
Not at all.
Lets see, at 5'10" I was 155lbs, throw in BDU/Boots for maybe 10lbs. Rifle & basic LBE was maybe 15?.
Maybe in a combat zone w/ body armor & a ruck sack loaded for a 3-day mission that might be light.
It's in the realm of possible for sure & leaves 80KG of bunk/locker each w/ some shared common area showers.
I've personally experienced WWII era berthing... those were four racks high with light tubing holding up canvas on which a thin mattress was placed. Even modern berthing uses light steel to hold up the mattresses. I wouldn't characterize airliner seating as "berthing", really.
Agreed, airliners is basically what you have on APCs. Okay, a bit more, but not much.
There is no 1 exact standard for the 4 berthing types.
Based on DS/JS Descriptions, current naval rooms, a few blue prints from BT products, I tend to group them as follows.
Officer = Single Occupancy small room w/ small restroom, possibly shared w/ a neighbor.
2nd Class = 2 Single Bunks in a small room & a shared restroom for every 2 rooms. (My active duty barracks actually)
Steerage = 2 Double Bunks in a small room & a shared restroom down the hall. (Basically Jack's room in Titanic exactly.) (Or some of my Basic training small rooms)
Bay Quarters = Navy Triple Bunks basically a mat w/ curtain to draw closed, exactly how DS/JS describes the MW Bay Quarters. 4 racks of 3 Bunks high w/ Wall/Foot lockers. Or Possibly WW2 era barracks w/ a large room & lines of bunk beds & a shared restroom at 1 end of the bay.
Finally,
Cargo Bay = Gymnasium Shelter housing, IE, cots w/ blankets & everyone's bags on the floor.
There are counter examples for most everything.
Like the same DS/JS has the DS Crew in the same type of quarters as the MW/ASP, but they are not stated the same & have 2nd Class v/s Bay on the RS, but that's fluff for you.