Probably best we stick with beds that can be made at current workshops.
Not sure what you mean by this? None of those beds suggested require a different type of workshop, just a new reaction.
Having played Gnomoria, (best described as "Dwarf Fortress Lite with Stonesense built in",) they make beds fairly similarly to how it is being suggested. Beds are constructed by putting together a frame and a mattress. The frame is made of wood at a carpentry workshop, and the mattress is made of cloth (and stuffed with extra raw cloth fibers) at a seamster's workshop, then combined at a carpentry workshop.
In fact, I'd like to see something of a mix-and-match categorical token thing going on...
Frames can be made of wood, stone, glass, or metal, or eschewed entirely in a "just throw a mattress on the ground" bed.
Mattresses are made of a pile of softer material, or a cloth covering of a stuffing material. This can be leaves (harvest from trees/garden plants), straw (material from crop plants), feathers, wool, or box spring (metal coils with cloth padding). Mattresses are assumed to come with their own blankets and pillows.
Bed Quality levels:
Sleeping in mud: -5
No frame: -2
No bedding: -2 (This would mean an "Egyptian bed" of sleeping on a stone slab)
Stone frame: 0
Wood frame: +1
Metal frame: +3
Leaf pile bedding: 0
Leaf mattress: +2
Straw pile bedding: +1
Straw mattress: +3
Feather pile bedding: +2
Feather mattress: +4
Wool pile bedding: +3
Wool mattress: +5
Box spring mattress: +7
Each level of quality: +1
OR Masterwork: +7
Artifact: +10
You'd then have a bed quality rating of between -5 and 20. If you had some baseline level of, say, 10, you'd make it so that dwarves get rested 5 times as quickly with an artifact metal box spring as sleeping in the mud, and they'd have skyrocketing happy thoughts.