Can’t put a tow bar on & no roof rack available so boot lid mount only option. After having a near miss when one came off a car in front of me on s dual carriageway so personally I think the strap ones should be banned. Thule used to do a rigid clamped one, but that was car specific so no joy. Only option is bikes in back of car with seats folded.
The force that is applied to a rear mounted bike rack especially if it is a high mount one with a bike taking the full force of the wind side on to the bike are immense.
The bike rack in question isn’t Zoe unique, it is Zoe amended i.e. It has been slightly altered to properly fit a Zoe, but the general design is generic, but the fittings are specific so it fits properly but isn’t designed specifically with EVs in mind.
We have a Halfords high mount bracket which we have used to transport bikes on the back of my wife’s Qashqai. The mount is stable on her car and you can’t see the bikes moving. It’s strapped on in six points. I’ll have a go at fitting it to my Zoe tonight and will let you know if it works ok. The top mounting straps have plastic dumb bells which you place inside hatch so it spreads their load on the inside of the car.
What type of bikes are you looking to carry? I can get 2 racing bikes on it easily, some mountain bikes have odd shaped frames and might not fit so easily.