The difference in charging speed that the 8 amps will give you is insignificant from a practical point of view. I'd not bother with it. I also wouldn't count on it to adjust for an incorrect setting.
I currently have an HPWC (new version) installed for Model S (72amp onboard Charger) on a 100 amp circuit (sub-panel)
Ran Conduit & prewired for power to the 2nd Charger from the sub panel. Have a Model 3 on order for delivery in April.
Purchased the 2nd HPWC to install next week.
Looks like I need to run signal conduit too.
In your setup, what type of wire do you have in the 1/2” conduit between the 2 HPWCs?
The manual says “twisted pair” with no mention of gauge.
Excerpt from installation manual:
The signal wires between each Wall Connector should run in signal conduit. Use a 1/2" (13 mm) UL approved conduit hub to seal the signal conduit opening.
• If the signal wire is routed in the power conduit with the power wires, the insulation rating of the signal wire should be equal to or greater than that of the power wires.
• The maximum distance between Wall Connectors is 49 ft (15 m).
• Use twisted pair cable for the signal wire.