Responding to the slow tow matter...
I've written on this subject here on RAS before as it's one of my pet pive safety concerns. I've had a few seriously slow tows with water. My experience is that you will drop into low tow whether you want to or not - there's no choice to be had. In the extreme case, expect to be hanging lower than "low tow" at a high pitch angle slamming alierons to the stops. When this ocurrs at low altitude, there's no possibility of recovering should you disconnect from the rope.
I now keep printed instructions for towing with water ballast in the side compartment of my glider. If I don't have the chance to talk to the tow pilot immediately before the tow, then I will have the ground crew deliver written instructions to the tuggie as I'm being hooked up. Written instructions are less likely than a radio call to be confused, forgotten or misunderstood.
Here's a pdf of my written instruction sheet:
https://drive.google.com/file/d/0B_X...w?usp=drivesdk