Now I have a second small PC (a small Asus X101CH netbook) the possibility exists for me to try some VLF earth mode tests with WSPR. Although I did receive G6ALB 3km away on 8.97kHz through the ground when Andrew was running around 40W, I have never tried looking for my own signal using WSPR at VLF. Theoretically it should be about as good as QRSS10, so quite weak signals may be detectable.
One idea I have is to TX the actual WSPR tone frequencies at baseband through the ground using my small 5W VLF transmitter. Using either my loop antenna or E-field probe on the car retuned to around 1.4-1.6kHz VLF, I can take some trips into the field to see how things work out.
With stability not being an issue I could even try WSPR15 (15min TX) which has performance close to that of QRSS30. Mind you, waiting at a test site for at least 15 minutes for a result could be tedious. This is where some local help from other decently equipped VLF listeners within a 10-20km radius would be very useful.