There are lot's of "cross" skis out there, tho' current marketing "wisdom" would have backcountry limited to "narrow" (w/light boots and "system" bindings) or "fat" (w/plastic boots and cable bindings). However there is a whole universe of challenging, and steep skiing between these.
Karhu has the best selection, tho' they just changed all of the names of their skis. I've got a pair of Karhu Outland (old name) which are waxless, around 65 mm at the tip, and compact (190 cm for 6'1", 175 lbs.). These have a part metal edge (they turn faster than full edged skis - impt. for skiing tight trees in New England). I spent Thanksgiving weekend skiing some fairly steep and narrow hiking trails on these plus an old pair of Merrel leather low-cuffed tele boots.
I've also got a pair of Karhu Pinnacle (old name), which are waxless, probably around 70-75 mm at the tip. My girlfiend uses these, as I find the full metal edge sluggish in initiating turns in the brush.
For steep backcountry I use an old pair of 190 cm Trak Bushwackers which are 90 mm at the tip, waxless and part-metal-edged. Tho' I generally use the Rotafella 75mm tele binding, I attached a pair of simple cable bindings which do give more lateral support. The Bushwackers float fine in powder, turn quickly, and hold on ice due to the middle edge.
Most of my friends, however, use the Karhu Catamount (old name), which is a full-metal-edged version of the Bushwacker.