I think you may be misuderstanding the Public Key advice.
I wish I could claim credit for the PKE idea (illustrated below), but he understood what I meant correctly. The advice I gave was based on the fact that the OP only said that the laptops used the data. Since I wrote that post, he has changed the requirements such that the laptops now collect the data.
work db secret db
(laptop) (under lock and key)
+------------+ +-------------+
| public key | | private key |
+------------+ +-------------+
+-----------+---
| public id | ...
+-----------+---
| public id | ...
+-----------+---
| .
| .
| .
The public id would be the real id encrypted using the public key.
