Yes the purpose of the handle is to carry the board with a rig, mainly on land. Without rig it will be unbalanced.
I made a mistake when I wrote we have a 500 meter standing depth area.
I meant 500 meter difference between high water line and low water line, tidal height difference being about 6 meter sometimes.
But getting throught the shallow shore break zone with white rollers pounding on my head, carrying first pulling by the top of the sail, then pushing the gear through the impact zone, always wanting extra 2 hands, the sea bed ondulating a bit so not being able to start immediately when the foil is free, feels like a 500 meter ordeal. Lately I developed a technique I call upside/down waterstarting : when the water is around my chest I keep the foil upside but start like to waterstart while swimming with my legs so little by little I get pulled in the sea with the sail pressure (but sometimes the wave pressure wins on the sail pressure and I reverse back to the beach, and then revert to the older struggle technique). Once further out I try to waterstart with the foil in the water but don't let myself pull on the board right away but stay in the water for some extra meters because the sea bed is not flat and I could hit ground again.
Now I'm carrying the board and rig in 2 times over the 500 meter on land.
Lately I tried to carry the board on with the mast on/in my shoulder and the board on my back while balancing the sail with one hand. I call it the Jesus Christ style, most wingfoiler do it that way but their board is lighter and they only have a light wing not a windsurf rig. This works, not easy with the sail, sometimes I use the front foil as a sail stabilizer. But the mast hurts in my shoulder. Then I put some radiator tube insulation foam on my shoulders round my impact jacket as a protection. Is better but still hurts. Maybe I have something else I will try : I have special shoulder pieces from a motor bike impact jacket Leatt, 3df plastic.
There is also another way, but I'm not going to go that way anymore.
For many, many years I carried my windsurfboard and sail on my head. First the sail on my helmet, and the the board on the wishbone, holding the board with one hand, one hand free, turning the sail and board upwind or downwind as the wind shifted. I was quit good in this, could do it untill 35 knots. Always did this at the end of the day coming back when I was tired.
A small advice : don't do it. This is very bad for your spine, especially C6 - C7 because of the weight and mainly the movement of the board and rig.

Believe me, now I'm OK but I will never carry things on my head anymore, like women in Africa carrying water bottles (if interested I can find a statistical study about it).
So my first thought was to carry foil board and rig that way, what would be especially easy for entering the shallow impact zone. But for this reason I will not do this.
I also saw a video of Balz Muller putting the board with the foil on the beach with rigg on the board, getting with his head under the board and lifting it that way. I think this is also a problem for C6 - C7. He gave it as advise for entering. But he is still young.
So right now I'm thinking :
- Jesus Christ style with shoulder protection, although this also pushes my spine and in a asymmetrical way.
- Using rope of belt between front foot straps or around the fuselage/mast.
- Installing the insert handle.
- Suction handle will maybe come off because of the concave form.
- Walking back and forth 2 times. By the way I carry the board holding 1 footstrap and the fuselage between front wing and stabilizer. Works quite good and the mast and stabilizer give a certain suspension feel when I run down the dune.
- Getting assistance of foil board sherpas

Any ideas are welcome, also systems for easier getting through the shallow impact zone.