Quiet times and parental paranoia

My younger son is away at camp and has been for a week. The house seems very quiet. In fact, it is very quiet.
Like, I presume, most parents, I am enjoying the respite. I get to sleep in an hour later on weekdays because I don't have to drive anyone to school or, for summer, day camp. Older son has no one to fight with except myself and his father. Fewer people to share the TV, computer or to quibble about what's for dinner.
Of course, I miss him. I had two little birds in my nest and now I come home and one is gone. Like the bird, I'm puzzled about what to do about the absence.
We get to view random pictures of camp activity. Some one takes photos daily and posts them on the internet. I sort through the set for one of my son. Then I pore over the shot for information. Does he look happy? Does he seem to have made friends? Is he wearing the clothes I had to buy to prepare him for camp? Does he look tired, sunburned or bug-bitten?
The speculation tends to become pointless after a while. But we're parents and we're not allowed to call and talk to him. Camp rules make your child theirs for a few weeks. We can e-mail him daily but he cannot e-mail us. He can write letters but writing is not his strong suit.
Suddenly, wonder of wonders, we get two postcards. Here is the text of one, misspellings and all:

Dear Dad + Mom + (big brother)
I was just writting to say that the first day was ok. The food is great Please mail me back as soon as possible. Please give more flag posts (I think he means stamps--the ones we gave him have flags on them). Love (son) to family
With all my love
xxxs and ooos
(Son)

Isn't he sweet? So of course I have mailed more stamps. And I've assembled a care package to send in the next day or so. But that's all there is. A happy kid living in a world created by big kids (young adults) for little kids. Lots of structure, like school but each class is "recess." Of course, it could be more "Lord of the Flies," after all these are middle school kids at their level worst.
Every day I e-mail him back saying that nothing has changed here at home. The cats are well, we are well. We miss him but aren't dying of sadness. If anything we are a bit bored. We omit the stuff that would make him jealous and want to return home. In fact my social life is the most active it has been in years but that doesn't say much. I've also finished a lot of books. But I want my son to imagine that we are all living in suspended animation waiting his return. Given a ten year old's thought process that probably is what he actually believes.
In the meantime, the keg's at our house.