Your 17 ohms base resistance along with the 2.5 ohm radiation resistance of this antenna means the radiation efficiency is 15%.

Are typical values of Rr and Rc for these antennas published somewhere? If so, you could calculate Rg by measuring Rt.

What kind of ground system do you have?

Twelve 16.7 foot radials at the moment. It's entirely possible I didn't measure the base resistance correctly. I used a 2 foot jumper between the analyzer and the antenna, so I was sitting pretty close to the antenna when I took the measurement.