1. EVSEAdapters has an extension cord but it's out of stock. NEW! Tesla Extension Cord – EVSE Adapters
2. The wall connector itself is weatherproof and can be installed outside with appropriate conduit and joints.
Why not install the Tesla Gen3 Wall Connector where you need it to be able to charge using the provided 24 ft charging cable?
As an alternative to digging a trench and installing conduit, wire underground it may be possible bury underground rated wire covered in cement. The wire would not have to be buried as deeply as when using conduit. No conduit would be required.
I have my Gen3 charger in my front stoop; so it is outside but is covered. The 24' cable easily reaches to my MYLR, and could reach over to a second car once my wife upgrades to a Tesla. The trick is to get use to backing in so that the charge port is on the correct side close to the Gen3 charger.
My exterior walls have horizontal studs inside them, hence the ugly gray electrical conduit. In a couple years we'll be redoing the siding and will put the wire inside the wall then. See photo below.
Since it is outside, I told the Gen3 charger to only charge my VIN. And I already have numerous security cameras.
MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021