It could be perceived as Fronting. The real question is who will be the actual main driver.

If the POLICY holder drives it more than the second driver, then it's fine.
However, if the secondary driver spends more time behind the wheel, then no - it isn't.

If the policy holder isn't the registered keeper, then the Insurers need to know.
Insurance companies (believe it or not) do apply a modicum of common sense - for example, with married couples sharing a car - they don't worry too much about who drives it more - they base their price on the greater risk driver anyway.