Re towtrucks, That would have been me.

General running costs (excluding petrol) are probably about double that of an A-series. Fuel costs is about the same if driven normally.

If things are in good condition, it should last 5-10 years with maybe a clutch change and maybe a set of plugs.

If you insist on driving like a hoon, expect to go through clutches every 2 years, factor in a broken diff or 3 depending on the size of diff you choose. CAs are reknown for blowing heater hoses, unless you replace them all, and remove the small lines that heat up the throttle body and rear of the plenum, trouble will ensue.