That is not 2:1!

2:1 at the lower half of the mast pulling 1:2 at the top

2:1 v 1:2 = 1:1

If you actually did manage to get 2:1 halyard then you would have approximately 9 meters of extra halyard on the deck with the kite is hoisted.. MADNESS!!!!!

Have always had a separate tack on my cap, it wasn't setup particularly well and tended to not cleat and be a bit painful to use but after a lot of tweaks it works every time reliably. the aforementioned advantages are well worth the effort.

The only thing I would add is having the tack line tail taken back up the tramp is not for me. I prefer to have mine shock corded to main beam, it leaves about a 1 meter loop on the deck but when the kite is being doused there is no friction added to the system. better for the kite, better for the crew.