Don't use RTK. Just WAAS.
I use the T-2 to report the position of my geophysical instruments in real-time. The smallest sensor is 1 meter wide, the largest is 3 meters wide. The T-2 generally reports a position under open sky of 0.5-0.8 meters accuracy, which is fine given the size of my sensors. I have the T-2 setup to send a position to my dataloggers every second, my datalogger software interpolates instrument positions between these points.
The problem is when I have mixed open sky/canopy project sites. Then this happens:
I didn't really make incursions there deep into the woods, the T-2 just suddenly reported a position 20 feet north and the datalogger software interpolated so that it looks like I did. The SiRFStarIII reports positions of ~2 meters accuracy under dense canopy, which is larger than my sensor size, however the pass-to-pass precision of the SiRFStarIII chip is about 1 meter, so it's still useful for mapping.