Eye-Fi don't run stable for a longer time, the camera must be restarted (manually) from time to time (it was reported at least after some hundred images)...
Are you sure with gphoto ? I thought it should work...
the SDM (Stereo Data Maker, a CHDK fork) can switch between playback and record mode from a running script, it should be possible to transfer the images automatically when the camera comes to playback mode; in playback mode images normally can be transfered via PTP (Picture Transfer Protocol).
You can have a look to the SDM homepage
, especially to Image uploading
, Uploading to the PC at regular intervals
and also to Continuous immediate uploading to the PC
The first two links points to a Windows solution (WIA-Loader, a Windows .NET app) - but the WIA loader is widely MONO compatibel, maybe you'll get it to work under Linux (or Wine).
The third link points to a solution using the commercial application "PSRemote", also a Windows application, but maybe this will run under Wine...
But first i'll give gphoto a 2nd chance, maybe you'll find a solution, it's a pretty nice & powerful framework...good luck !