The most traditional Swedish quality is cotton 16/2 sett at 36 ends/cm (roughly 90 ends per inch). Sigrid Palmgren (1923) also has cotton 20/2 at 40 ends/cm (100 epi) and cotton 30/2 at 57 ends/cm (142 epi). Maybe not for the faint of heart... and probably not for the front-to-back method, etiher.
Susan, as I said - this is at best a total compromize of a loom: it folds, is easy to transport, lightweight... but not a "working loom": the castle is too low, the total warp distance is too short, there are no lamms (which causes the treadles to drag the shafts sideways). It is the only counterbalance loom I own, and also the one truly portable. My only point in posting this "project" was to show that there are *no* problems making unbalanced sheds with a CM, not even with not-very-good CM.
And yes - it is entirely possible to weave double layers on a loom like this.
I have woven double layers even on the sort-of-hopeless compromize of a loom shown here. Swedes have been weaving unbalanced counterbalance sheds for hundreds of years before someone told us it was impossible - so I photographed the "project" linked to, just to show... (Granted, I do prefer countermarche looms, but that is not the point, here)
On my website, I have a couple of articles on how to construct double width (ans also double layers, interchanged). Here is the link to double width (part1).
And MaryMartha, of course it works on 8 shafts, too (or 16, or...). I have never tried it, but I can't see how it will prevent draw-in; to me it sounds like there is instead opportunity to get draw-in at *both* folds (instead of only *one* fold line)... And, unless you thread your top layer on double the needed shafts, it will be awkward to insert the shuttle in he middle. Unless there is a wide gap, of course :-)