Our freeze line in CT is 42", but I had the same worries as you about the main drain.

Considering the main drain would be the only plumbing line I would never replace if it ever broke (waaaaay too deep), Id rather spend the extra $$$ and make sure I take care of it correctly. The blower I bought from Pools Etc. actually launched the water out of the main drain so far that it went thru my (already installed) mesh safety cover. So basically it sent the water 2' above the surface, from 8' down. 10' worth of push is pretty darn good!

BTW, I used my air compressor (or tried to anyway). I even borrowed a tool that increases air flow (using a venturi effect). I was still not able to push the water thru and out of the main drain. The right tool for the job really is that line blower.

Re anti-freeze....I dont use any up here. Its been suggested to me, but Ive never thought of it as necessary. However, this year I may throw a little slug of af into each line. I know some people completely fill the lines, but with the line blower Im not worried about making the line completely filled with af, just want some in there to handle the spots where water will end up hiding (low spots, elbows, etc).

-Chris