Good advice above. Some comments:
1. The plan to use 'free' superchargers and charge 120V at home will get really old, really fast. Even if the supercharger is fast, sitting there for 30+ minutes just to save a few bucks will get annoying. And how many times do you need to wake up to a quarter full Tesla before you give up on 120V? L2 (240V) home charging is great, just plug it in (like your phone) and its always ready to go. And the price is sooo much less than gas, esp given the higher eff (mi/kWh) of the Teslas.
2. About the outside/rain factor. The entire POINT of the EVSE, instead of just plugging in your EV, is safety. The contacts on the EV connector are DEAD until after its plugged in AND a microcontroller has determined that the ground contact is made and a suitable handshake exists (i.e. its plugged into an EV, not your wet fingers). So there is no reason you can't stand in a puddle in the rain in your bare feet and lick your Tesla connector to see what it taste's like. Totally safe. And a level BEYOND the safety GFI provides. You are putting in GFI to make codes happy, not bc of any safety factor.
So this is where the plug comes it. The plug/outlet is the only unsafe part of this plan, esp re weather. I would put the outlet in an 'in service' weather box. The in service box has a notch such that the box can be closed with the plug/cord in place. And then I would just leave it plugged in ALL THE TIME. The EVSE and its connector is sealed and weather-proof and engineered safe that way.
One issue here is if you want to carry that EVSE in your car when driving. In this case, I would just get another one and leave it in the trunk (it will never get used). Another issue is theft.... a thief could steal an EVSE left outside all the time. If it happens, just get another one for $150 and lock it somehow.
3. Rusty, if you are confused, keep in mind that the EVSE and the EV talk about what current/power to use, and decide to use the lower of their two capacities. The EV might take 50A 240V, but plug a 16 A 240 V EVSE into it, and they will agree on 16 A. No problem.