The Cambo is BIG and heavy - how rigid is the rear standard of your 4x5? Also, there are mixed reports about film flatness in the Cambo rollholders (also sold as Calumet).
Other options beside the Horseman:
Sinar Panorama, Vario, Zoom, Zoom2: Also big and heavy, and a nuisance to load, but well made and probably the flattest pre-exposure film path you'll find in a 6x12 rollholder. The Zoom2 is slide-in only, the others have grooves for Graflok sliders too.
Linhof Techno Rollex - if you have lots of $$$$. Graflok only.
Cheap Chinese-made rollholders, under various brand names. No autostop on film advance - count frames via ye olde redde windowe. Graflok only.
I've owned a Sinar 6x12 as well as Cambo and Horseman rollholders in other formats (Toyo too, but they don't offer a 6x12). If I were buying a 6x12 holder again, for use with a lightweight 4x5 field camera, I'd probably go for a Horseman as the best compromise considering cost, size, weight, construction quality, film flatness, and convenience in use. If I were near-broke I'd get one of the Chinese holders and not lose sleep over it.