I attached my boom gooseneck directly to the mast, several inches below the end of the track.  This allows the boom to stay in place while the sail slides can come off the end of the track.  I also have that screw stop that goes into the bottom hole of the track to retain the slides.  The whole assembly is predicated on how high you can haul the yard before the halyard shackle hits the sheave.  Once you establish that, the sail tells you where you have to locate the gooseneck.

   You can certainly do either a fixed or moving gooseneck.  I've sailed dinghies for a lifetime, and even the professional builders/designers of various popular dinghy class boats don't seem to have ever decided one way or the other. 

With the sail being provided (as shown in Captain Skully's picture) he has a consistent grade of sailcloth right down to the foot (as would be expected for a loose-footed sail), but with a fixed tack and cunningham.  I'm sure that it all works, but in higher winds you'll be cranking on the cunningham and outhaul to flatted the sail, and - possibly resulting in a fairly big wrinkle and a bit of "flappy" sail along the foot. The picture already shows the beginning of the wrinkle. 

Even in dinghies with a fixed foot sail (sail attached along the length of the boom), in an effort to maintain a nice, unwrinkled sail shape as low as possible on the sail, more modern sails are being designed with a panel of softer sailcloth along the foot.  With the outhaul and downhaul tight this creates what sailors call a "shelf" in the sail.  Sail trimmers will refer to the size/appearance of the shelf when trimming for various with conditions. 

I looked at the Passagemaker pictures on the kit sail portion of the website and note that with the aluminum mast they are rigging with a downhaul on the boom and/or to the tack of the sail - no conningham.  I'd try to accomplish that on your Passagemaker, even with the wooden mast.

Refering back to Captain Skully's picture above (and of course this is just me) I'd rig the goosneck-to-tack connection like he shows, but substitute for a sliding cart on the boom end of the the gooseck universal that will fit your sail track.  The portion of the track going up the mast that takes the sail slides I'd leave alone, with the bottom of the track at about the height shown.  I'd leave a gap of about 3-4 inches (just enough to fit the gooseneck slider) then add a second piece of track below, with plenty of excess to provide room to pull the boom down with a downhaul, even on an old, stretched out sail.  The length will also increas the number of screws holding this shorter length of track onto the mast. Just not so long that the boom slides down to an annoyingly low height when not rigged with the sail, and not so long that there ins't room for some type of downhaul cleat or whatever below the track.  Put a stop at the bottom of the track to support the boom when the sail is lowered.  

In rigging, you might develop a system where it is easy to detach the mainsheet from the boom. You then could avoid ever undoing the outhaul and routinely just pick the boom up off of the track and roll the sail around the boom.  Or even find a gooseneck with a unversal that allows the boom to spin.

Anyway, my two cents, and as I said, the history of dinghy design proves this issue has never been decided.  Not being a race boat, whatever you come up with will be good enough.

Bubblehead makes some excellent points.  I do have a downhaul that connects to the first slide grommet above the tack cringle.  When tensioned enough to take the wrinkle out, it does create a bit of a bag as if reefed at the foot of the main.  Also, my boom, located as described above is at the lower limit of what I would consider comfortable/safe.  His sliding gooseneck is a great idea for tensioning the sail, but if my boom was any lower it would definitely interfere with passengers sitting forward and make it more difficult for me to tack.  Racelite makes goosenecks for either configuration.  http://www.racelitehardware.com/goosenecks/

Also, with the battens in, the sail doesn't scandalize very well.  With them out, you can gather the main up or down as needed.  I keep my main laced to the yard and put it in the bag as such.  The mainsheet quickley disconnects from the boom with a snapshackle/padeye and the outhaul just runs through a cheek block to a small cleat.  Takes just a few seconds to rig that part.

   Thanks so much for your replies - I was concerned that having the boom on a slide might be an ill-advised concept for reasons I'm oblivious to! Your thoughts have been a great help. I already have the sliding goosenecks and enough track, so I think I''ll give it a go.

If at some point it seems like it would be easier to have a fixed boom, I can always change, I guess.

Thanks again

P

If you don't use that sliding stopper as a hard stop for the upper bound of your sliding gooseneck, you'll have to set the main, then harden up the downhaul to lock your gooseneck in place.  I still have the extra track and can always get the gooseneck at Fisheries, so let us know how it goes.