Raven, or whatever they are called now had some longer units that could suffice. $$$$
The old SA stuff was really held highly by those with them.
ATC, not the studio monitor company, made some 2' long unit planars.
BG Neo8 or Neo10 or the GRS clones are options.
Finding some Monsoon units could work.
Beyma TPL150 can play fairly low.
ESS Heil are low reaching AMT tplanar.
OP, your query says 'ribbons', which can include the variety of AMT, planar, true-ribbon, leaf, etc. I will say that all of the above are within this group type using flat, or flat and folded membranes suspended between or inside a magnetic field. Have a large midrange reaching true-ribbon would be difficult and very expensive due to the onboard electrical transformer requirements. The largest true ribbon I know is the RAAL lazy ribbon, but I don't feel it dives deep enough to be called a midrange.