1. Best practice is to find a 110V and plug it in. No one is inconvenienced and charge level is, at a minimum, maintained.
2. 3-10 days is really nothing unless you're low on charge. Also if it's very cold the car will wake up periodically to warm the battery.
3. A number of EVSEs charge by the hour whether they are suppling electricity or not. This can get expensive.
4. Be sure power saving (sleep mode) is enabled.