I think nearly all USB devices which provide internet connectivity require drivers specific to the OS they are connected to. Combine this with the fact you cannot load modules/ drivers to an IOS/ IOS-XE/ etc device means this is not a supportable option.
Nice idea though! :)
actually, think a lot of the RV routers do support dongles, such as the ones below. You need to search for the model and use they keywords 'USB Compatibility Matrix'.