I think I’d be tempted to get a J1772 extension cable instead of an extension cord. The reason I say this is there have been a few times a charger on the road has been out of reach and carrying one in the car would help.
Something like https://www.amazon.com/Lectron-J1772-Extension-Compatible-Chargers/dp/B0821FCF7P
Amazon has extension cables that you can use for charging overnight: https://www.amazon.com/dp/B0821FCF7P
If all you need to do is add length, they do make j plug extension cables.
https://www.amazon.com/dp/B0821FCF7P/ref=cm_sw_r_cp_api_glt_i_19GAB9SR7B33R0395NXB
There’s options like this out there which are kinda what I mean:
https://www.amazon.ca/Lectron-J1772-Extension-Compatible-Chargers/dp/B0821FCF7P
Something like this will do the trick: https://smile.amazon.com/dp/B0821FCF7P/ref=cm_sw_r_cp_apa_i_eSdtFb4GS2XCC