There was a great missed opportunity stuck between wet workshops (unworkable) and dry workshop (much better, but takes a Saturn V).
See Bellcomm document attached.
It was the SLA : Saturn Launch Adapter. It was a fat cone that linked the 6.6 m diameter S-IVB to the 3.9 m diameter Apollo CSM, and provided a home to the folded Lunar Module. That fat cone was 200 m3 in volume, which is twice a Salyut (100 m3) and almost two-third of Skylab (330 m3).
The Soviets created the first generation of Salyuts (DOS-1 to DOS-4) by stuffing Almaz hulls with Soyuz ECLSS guts.
NASA could have done something similar: stuffing Apollo ECLSS guts into a SLA, let's call this SLA-station or SLA-S. The whole thing launched by a Saturn IB, of which a surplus existed post Apollo 7, which expanded booster 205. AAP has ordered Saturn IB up to -216, so 11 boosters were available. Although from 212 onwards they were uncomplete or not even assembled.
SLA-S would have a multiple docking adapter for ATM later. Baseline mission: two launches, one for the SLA-station, one for the Apollo crew. The SLA dry, pressurized module stays attached to the spent S-IVB. Why ? because wet workshop will return. The S-IVB outfitting however would be done from a 200 m3 SLA rather than an Apollo 6 m3 ... should be a little easier no ? Let's call this SLA-WW.
What truly matters is, even if the wet workshop outfitting fails, the Apollo crew still has 200 m3 of dry SLA module. But if it works, the LOX and LH2 tanks add enormous volume to SLA-WW.
Skylab turned the S-IVB's LH2 tank into an habitat but the LOX tank was used as a giant trash can.
This link tells me a S-IVB hydrogen tank was 10500 cubic feet and the LOX one, 2830 cubic feet. That's 297 m3 and 80 m3 respectively.
https://www.enginehistory.org/Rockets/RPE08.30/RPE08.30.shtml
Skylab 330 m3 is the LH2 tank volume plus additional MDA and ATM pressurized modules.
So the SLA-LH2-LOX combined volumes should be approximately 650 cubic meters. Not too far from the ISS as a whole : 1000 m3.
By evenly splitting the 11 Saturns between five Apollos and five SLA-WW, five missions could be done. The 11th Saturn would be in standby for rescue.