There aren't many in that size, true. The Seneca catalog that listed which films were for what cameras had a list of 22 different cameras using 122 film, but only six that use 125: this one (Seneca Box Scout #3A), the #3B Quick Focus Kodak (that's the box camera where the whole front moves in and out), the Stereo Brownie, the #3B Folding Hawk-Eye, the #6 Weno, and the Ansco #3A.

The spool is necessarily a little wider than the film, though, or it would get stuck. 122 spools are 3.715" long, or about 0.09" wider than 3-5/8".