It also depends on where you go. For example, Ottawa is the land of opportunity for Class B. Other larger bases also have a number of positions. Otherwise, each Reserve Force unit will have a small cadre of Class B postions (typically a couple of Supply Techs, maybe an MSE Op, and a pair of FSA, and an HRA. They will also have one or two positions that are more relevant to the main role of the unit. Brigade HQ will typically have a number of Class B positions, and some are generic in their occupation.
Lately, with such a dire shortage of HRA, many units are hiring out-of-trade people into their Orderly Room. We've had Medical Assistants acting as Clerks for a long time. In Ottawa, many positions are written for 'General Service Officer' or the equivalent for Non-Commissioned Member.
Logistics Officers have many opportunities in Ottawa - though that's mainly at the Captain/Major rank. Officer Cadet to Lieutenant are not fully trained, and there's few Class B Lieutenant-Colonel positions in any occupation in the Canadian Armed Forces. For Supply Techs, there's a broader spectrum of opportunity from Corporal to Sergeant/Warrant Officer. Above Warrant Officer positions may exist, but tend to be very limited in number for Class B.
Feel free to ask any questions. I've been Class B or Class C since 1997, in Hamilton and Ottawa.