Thanks Ray,I appreciate you sharing the details.
It is interesting that you use the verticals without a ground system at the antennas. It might be worth experimenting in this area, along with the 25:1 transformers. I've had great luck using local grounds and transformer isolation in this manner (mostly distilled from the writings at W8ji.com on connecting Beverage antennas). With my long-wire, a good transformer with lots of inductance makes a big difference (at LF-VLF) in preventing noise on the coax shield from adding at the antenna connection.
It's easy to check what noise is coming from the shack - disconnect your feedline out at the antenna connection short it out, and listen. That's the "gunge" you risk adding to the signal. If you can also connect a battery powered receiver out at the antenna, avoiding the feeder run, it's possible to assess the interference it receives and compare against the common mode stuff coming up the coax to see which is the bigger problem.
OTOH, if the phase canceler can take care of things, then all well and good.
Good discussion!
Ed