Looks interesting. Only problem is your leaving fire unattended for many hours, and you never know what fire can do. If its dry and windy outside I would avoid this, but if its moist and the wind is calm, it looks like a pretty good idea.

It looks really easy to make too!

That's why I was thinking of using small tabletop BBQ grills. I have seen some at Wal-Mart for $20, you could leave the top on and open the vent and it would still give off plenty of heat throughout the night. To be safe you could sit them on some cement pavers.

Where I live it gets windy when a cold front passes through, but the hard freezes come afterwards when the wind has died down and the frost settles.

Here is a link that might be useful: bbq grill

when they use them in FL the are awake supervising them all night and the orange fields are unlikely to catch fire - but around a house and going to sleep sounds too dangerous.