I had considered getting a whisker pole for my Mark 11 until I talked to a C40 Mark 11 owner that had one on his boat...he said he has rarely used it (got it cheap from a friend) primarily because of the position of the forward stay which restricts the aft movement of the pole...take a close look at the angle that the pole will be at...it might not be enough for that wing-on-wing thing you probably want to do. As an aside, his recommendation when running downwind was to sheet in the main a little more than usual and "dump" the airflow from the main into the genny....I tried it and that works pretty well

I have avoided the whisker pole, too. I fly an asymmetrical spinnaker when I can.

For lazy downwind work with just the main and Genoa, I will often prevent the main boom on the windward side (sailing by the lee), and then the Genoa stays full without a pole when I run at 150 degrees apparent wind angle. I can run dead downwind in a decent breeze if I am careful, but I prefer to run 30 degrees off and it keeps things simple and safer.

Good topic, I was considering one for Hilbre but will take a closer look at the forward stay when I am on the boat this weekend.
John Meyer
Hilbre 2135 San Pedro, CA

I run a pole on Solstice when we race. Installed a track on the front of the mast with a car to connect the pole to. The pole is just long enough so when it is fully retracted, it will "dip" below the drum without having to unhook it from the mast. I am using attachments on the stanchions instead of drilling into the deck. This way I can also remove the pole, and its components, from the boat.

Without a pole, I have done the opposite version of Vic's solution. Same concept, different position. I over trim the jib, just past the mast, to "catch" the mainsail air. This allows me to keep the boom out (on deeper angles) and reduce an accidental jibe of the boom. If the jib flutters, it is forward and out of the way of people on board, but for the most part, the mainsail "exhaust" will keep it full. I have used this racing when the wind is way up and I don't want crew on the deck. Based on the distance of the legs, I have had better results doing this than wrestling the pole up and down in heavy air.

Good luck.