| The foam core construction fell right in with my objectives.

To be clear, that is the objective of 3500# payload, right?

| Likewise the offset mast......a design feature which I have not yet become entirely comfortable with.   

I found this link of a kd 860 for sale. I include it because it has offset mounted Aero junk rig, which seems relevant to your interests.

https://www.apolloduck.com/boat.phtml?id=558987

It might show you what kind of rigging is needed for your one mast.

| I do want the main portion of my junk rig to be able to fly over the boat on those points of sail where it is oriented mostly laterally.  

Do you know why you want that?

| How much difference in performance is there is real world sailing with the camber 30% aft of the luff, or at the 50% point?

I guess it is a third order variable. Aspect ratio being first, foil profile being second. IMHO.

| Theory says it should be significant, but theory is not always borne out in real life sailing.   An example is the "good tack / bad tack" belief.
   
| This is relevant only in pointing out that our expectations are often not borne out in the real world. 

The whole world is like this I think.

|  I rather like the idea of having the option of hanging the main sail well over the side, or hanging it over the boat. 

Have you thought through how the rigging will work? Perhaps some listers have some advice?

| The boom will be quite long, as the aspect ratio will be low.

Long booms are a concern as gybes become terrifying or, perhaps, high energy events?

| The mast will not be tall, standing only about 9M above the top of the bridge deck cabin....

|  The shorter the mast has both advantages and disadvantages.  I will be sacrificing ultimate performance, but the low aspect sail will have a great deal of footage for light winds.

This is a non sequitur. Tall masts can have even more sq. ft. Afaik, there is no advantage to a short mast, but I look forward to learning your thoughts.

| The junk rig does not flog due to the battens, so when faced with light and variable winds, I can have all sail up..... no flogging, no huge spinnaker inflating and collapsing and being a general nuisance.

Yep. Simple rigging is a big deal.

| I've long ago examined what I can do with the funds I have available to build, and what ongoing income I have, and this is a major driver, if not the major driver.   I'm a poor man, I don't have deep pockets.

You have not outlined your expected budget for this boat. If that's not a difficult question, an idea of your expected build cost would be interesting. But see below.

I tried to look up materials costs of the KD860 but was unsuccessful.

| Weight is proportional to cost until we start striving for extreme weight reduction, and then it describes a parabolic curve in the opposite direction.  Within a given weight range / cost range, the objective is to build the boat that provides the best living and sailing environment / most usable space.   The cat fulfills that very well. Cats increase rapidly in weight / cost with length.   The Woods Tamar for example, at 31 feet is almost double the weight of the KD 860 (stock) at 28 feet.  I don't expect the KD 9.  The Kohler Pelican at 11.5M has an empty weight of only 2200 KG, against the KD 860 at 1800 KG.   The weight per meter of length in this case is going down from 209 - 191 for the longer boat.   This is definitely the exception, NOT the rule.   Most boats go the other way.

Interesting thought. I would say this exception SHOWS that it is entirely reasonable to say one can design a longer, lighter boat.

For example, the 12m Ex40 is ~900 kg = 75 kg per meter. Is that far enough down the parabola?

At half the weight, it is reasonable to assume half the cost to build. And designed and engineered to be built in foam and glass with the fastest cleanest build techniques. Not a retrofit of foam and glass into a plywood build.

This is another reason I moved away from the cat designs.

| Increasing length just for ride and speed is simply not on the table here.   Those are NOT priorities.

You misunderstand. I chose a CHEAPER boat to build. The Cats are too expensive. Speed and ride are second order variables for me too.

| Note the way Bernd created a "wing"
<snip> The full length hull molds would be far simpler with only two surfaces, the bottom and the side.   The wing can be an add on
|separately infused piece.

Yep. You will note the HP design does this kinda stuff all over.

|  Note the temporary bulkhead used during bridge deck cabin top construction.  The cabin top is a compound curve on both boats, and will have to be built "the hard way".... hand finished both top and bottom.  There is no way to produce this compound curve with a simple mold..  It's a case where it's easier to do the job the "hard way" than the "easy way".  The only compound curve on the entire boat.

I think there are a few ways to to do it the easy way. How big is your build space?

P.S.

I think you should convert your Kg per meter figures into $/m.