I am using FKD 13x18 currently to produce a few still lifes. The camera can do the job, although be aware that it has no shutter (use slow film & long exposures), and is not exactly of Swiss watch precision. The movements are limited to front shifts and small tlilt&swing of the back; probably adequate for landscape work but is really pushing the limits for close-ups.
You can place a piece of cardboard instead of glass plate and stick film sheets to it. The cassete have a spring in the center pushing it to the focal plane. There are also special cassetes and inserts for sheet film available, but those can be hard to find.
The 13x18 kit weights 11kg, and 18x14 is around 14, so my sympathies if you intend to do street-shooting with those 🙂