Reasonably guesstimating the most recent time frame (4/20 to 5/7) it looks like i have averaged 7Km/a day (including rest days), running both in vibram 5f and barefoot.
Most kilometers run in one day was 20.5km.
When i was training for the marathon i wa doing a lot more but also using a pair of gutted-out adidas x-country because it was a cold/humid winter.
I agree if the grass is clear and good, its a shame not to go barefoot. Check it out first though. One extra run with shoes wont kill you.