Given the noncontinuous nature of a DRSSTC you may want to use fibre optic linking between the interupter and the driver board so electrical resistance of the umbillical is no longer an issue. All it takes is a diode and a phototransistor and some fibre. You add a lot of safety that way too, and it prevents a feedback loop problem (f0 getting coupled to the low freq interuption, which drastically reduces output).
I added about 2cm of a trace to the modulation input to my main SSTC's driver and it was enough to pick up the f0, this basically interupted the coil out of phase with the drive signal and reduced output to less than 2% normal.
Ohh and that breakout point has too much capacitance and will detune your coil when the streamer capacitance is added in to the equation. Use a shorter rod (no more than 3cm) or a much skinnier wire instead for improved results. Also limit it to a single break point instead of two.
Way to go on the build btw! I don't stop around LPF very often anymore but I still frequent 4HV, so you caught my attention there.
EVR is a top notch guy, he's been extremely helpful and offers great kits. I got my oscope from him for a total steal.