Oh, stocker photography is the stoker taking pictures while the tandem is moving with some aspect of the tandem present in the photograph to, er, prove it was taken while moving on the back of a tandem? Something like that.
There's also some photos in our Mini Tour [3].
Links:
[1] https://pancake.org/node/171
[2] http://www.santanatandem.com/
[3] https://pancake.org/bikes/tour2004
[4] https://pancake.org/node/173
[5] https://pancake.org/node/176
[6] https://pancake.org/node/177
[7] https://pancake.org/node/178
[8] https://pancake.org/node/182
[9] https://pancake.org/node/183
[10] https://pancake.org/node/172
[11] https://pancake.org/node/174
[12] https://pancake.org/node/175
[13] https://pancake.org/node/179
[14] https://pancake.org/node/180
[15] https://pancake.org/node/181