I'm going to speak to you as an electric vehicle owner.
Considering how cheap it is to plug in an electric vehicle to a 120 volt wall outlet and charge, It would probably make you seem like an annoying cheapskate if you disallowed electric vehicle charging or put restrictions on time frames for charging.
Let's do some math here real quick.
If I plug in my car overnight it charges around 70 miles. That's out of a 350 mile range. 70 divided by 350 is 0.2. so overnight you can charge the battery by around 20% if you plug in at about 5:00 p.m. and then unplug in the morning.
My car's battery is 75 KWH. Times that by 0.2 is 15. So that means you're charging about 15 KWH per night.
The average price of electricity in America is around 14 cents per KWH. So .14 times 15 is 2.1 dollars. Often times the price per KWH is actually half the normal price If you are charging it during off peak hours, so if they charge overnight it is likely to cost you around $1
So you're really going to adjust your rules to save anywhere from one to two dollars per night?
I'm just letting you know that as an electric vehicle owner, if you put any sort of condescending sounding rules or regulation about plugging into an outlet to charge a car in a garage then I would immediately move on to find another Airbnb because you would seem annoying and cheap to me.