Don't think a UC/ or VP endorsement would make a difference to the CPL training course (I don't think they are a requirement to sit the test either), since you could just build it into the circuit work and GH parts.
But, many courses do the CPL in an Arrow, or other complex single, so it's best to get some complex time, since you don't want to forget to put the gear down on finals - I guess that would be a fail.