Alright then , I'll ponder alone.....
I thought of what it would be like to be next to a foil under water at speed, it would be kinda like a wide Venetian blind blade trying to keep a stable angle of attack so it didn't stall.
Then I thought if the planing area is kept the same but it's length is parrallel to the flow ( like every fish, boat and surfboard) then it would be a smoother roller coaster ride. Simple concept.
Then I tried a few prototypes and it's true. The longer the craft the more stable it is, either on or under the water.

I know Craig 66, ****in amazing research eh ?
I'll accept a 6 pack of VB and a pack of pork rinds, nah, make that 2.

Sn, it's a common story with inventing, the money , the backers and then the protection of intellectual property is impossible to control nowadays.
The foil story is that current foil design is wrong for surfing waves. Sure it's fine for shoulder hopping but it's completely wrong for riding the normal breaking waves that we all ride. Do you really want to be in 6 inch surf when there's real waves available ?
It's like they've discovered Baseball but decided to use a golf club instead because it works so well in a similar application.
The current high aspect, NACA foiled concept is going nowhere. They've had a few years to change the design and make it safer, more stable, fun and affordable and it should be at around the $300 retail mark by now. If it was already a winning design, foiling would be mainstream but it's too dangerous, awkward to learn and massively expensive.
I know it's a prediction that no ones willing to believe but if foil design concept doesn't dramatically change it will be in a lesser place in a year and then rapidly decline into the realm of surfing inflatable dinosaurs.

what kinda design stuff you interested in?

www.facebook.com/Ellway-Aero-Hydrodynamic-Designs-671685749655101/ this facebook page has some interesting discussion

generally looking at the production gear out there from the big brands, you can see that some has been very well thought out, while others are worse then the knockoff ali-express crap you can buy for a few hundred $$$. There are a few off the shelf foil profiles you can use, which are documented in some DIY stuff you can find online, the Eppler series is probably the best starting point.

Pretty much like you say, longer fuselage is better stability. And if you have some adjust-ability in the angle of the rear stabiliser you will probably have something that works.

My main disappointment with the production stuff is poorly thought out or no thought put into corrosion protection. I don't have a single piece of kit that really needs to be disassembled or washed, but now I have this new fangled foil thing which the manufacturer recommends I completely disassemble and wash with fresh water... what a pita. Would cost them a few bucks more to use better materials.

That and you can see that some of the gear out there really doesn't justify the price tag on it, despite their claims of extensive R&D, it has obviously been rushed out. For the slow speed, light wind stuff, to get 80% of the way there is probably fine, the last 20% of performance probably makes little difference to the end user, but it would be nice that they got "simple" stuff like corrosion etc sorted.

It's interesting that even before you know what it's for, the moment you mention 'wing ' the mind draws a lateral extension off a fuselage. No thought for the long foil design that is clearly more stable.

I don't think it's going anywhere too soon....

If you have a look at the race foils, and the speed foils between the two of them, that;s pretty much the whole range covered.

I mean next year some one might bring out a 75cm span ultra light wind foil that can go out in 3 - 4 kts, but it's going to struggle at 30 kts downwind.

The big issue with trying to get lift from length, rather than width is the massive drag penalty due to vorticies

It's like comparing a glider gliding, and a rocket gliding after the motor is cut.

Still haven't tried out my new setup, but the foil is 60 wide, 10 mm thick. It felt a lot more slippery compared to my mates XR1 + freeride wing I tried out.