600w is a massive draw simply to provide cooling, and whilst you appear to accept this, I'd be avoiding this wherever possible.
The 'timer' is integral to the Rolec Wallpod, however a little investigation will reveal no standard timer can switch 32a so would be a risk of burning out. The professional way of controlling the charge sequence is to make use of the two control lines (the two smaller pins) one is the proximity sensor that detects the plug insertion, whilst the other initiates the the relay to turn the power on.
Never, EVER start or stop an EV charge by interrupting the supply in the way you suggest, it must be controlled to prevent damage.
On the Rolec, (which is permanently powered) complete with blue flashing LED, will on insertion of the tethered lead do only one thing. That is, show the plug inserted icon on the Fluence dash. It will not charge as the timer won't allow it until 0005. At this time, the contacts switch, the flashing LED changes from blue to green and the Fluence indicators flash confirming the charging has commenced. At the conclusion of the timeframe, the voltage on the pilot line drops and the car exits charge mode.
A number of the other domestic Chargepoints do not provide any timing mechanism, suggesting that it is up to the vehicle (or its app) to control it - the British Gas oval one frinstance. My original installers of the Wallpod refused to hook it up to my off-peak supply for this very reason - my radio TeleSwitch could manage switching 32a but the issue was bypassing the pilot line control, and firing in the 240/12v instantaneously then removing it, denying the car charger any element of control.
As to my charging cycles, I can confirm I still get a full charge from 5% to 100% in under 5 hours it has never taken longer