Over the past few days, I have been able to bit bang the I2C bus with the PIGPIO library. I found a very helpful example at http://raspberrypi.stackexchange.com/questions/3627/is-there-an-i2c-library/4052 which was posted by crj11. This example was using the pigpiod_if.h library. This worked well but required the application to be run with elevated privileges (sudo) which was not acceptable as I needed to run the application from a Python script which in turn was running every 5 minutes from a cron job. The final solution was to use the pigpiod_if2.h and run the pigpio daemon on startup.
The final solution has been running for a few days with three sensors connected over a total of 9 feet (~3 meters) of cable. The data has been logged at Adafruit.IO which I have made public. I may remove or rename the Dashboard in the near future so here is a screenshot of the page.
I have also updated the GitHub site for the project so there are now two releases available. Version RC_0.0.1 is the version using the hardware for I2C control and version RC_0.1.0 is the bit bang version.
I still have more work to do to make this project valuable to others. I plan to create some better documentation on the project and provide a full write-up to allow someone to follow along and build there own from start to finish. Right now, 80% to 90% is captured in various places but there are obvious gaps such as the connection to the Raspberry Pi. One can figure this missing information out by looking through the right source files and piece it together however I do not like it when I find a project write-up that is only 80% to 90% documented. It is still better than nothing or only 10% to 25% though.
I hope someone will find some of the information here useful.