I have some questions/criticisms about your modifications to Fetlar.
1. No draws are allowed. Draw fort formations, where the king is free to move inside an invincible formation of defenders, have no special meaning.
Would this not just create an infinite game? A white player in a draw fort with infinite movement and no possibility to win would have no incentive to end the game. Would not an AI simply move forever creating an infinite an unending game since the players can no longer agree to a draw(as is customary in such a circumstance).
There is a qoute from Crust on here explaining the draw fort as a strategy that this rule modification would annul.
... white may as well try to break out and seize control of a corner, and then go for a draw if that fails, and black manages to complete the encirclement. The interesting part comes when black realises that white has started to do this, and must work out how to stop it - often black will have to risk exposing a corner in order to prevent white from achieving the draw position. If that happens, white may have another chance at a win. So white is using the threat of a draw to disturb black's position, and thus create chances for a win. ... I don't see anything wrong in using the threat of a draw in the mid-game to get some leverage over black, especially after black has completed the encirclement - I mean, what else is there for white to do, apart from waiting to die?
Completely removing draws would in theory remove one of the key strategies Fetlar has and would instead likely introduce infinite games.
2. If the defenders are fully surrounded (that is, if no defending piece, given an unlimited number of moves from the current position, with no responses from the attacker, can reach the edge), the defenders lose.
I assume this is just the surround rule that's employed on almost every variant here. It's a good rule as it ends the game for black slightly quicker.
3. Board positions may be repeated a maximum of two times. On the third repeated board position, the player who made the move to enter the repeated position wins. (Read another way, this means that the aggressor—the player who is forcing the threefold repetition—loses.)
This rule as it is here just seems to remove small draw forts. Which if allowing draws would slightly tilt the balance to the favor of black. But as you cannot do a draw fort this would only seem to end the game in situations in the rare instance black does not have enough pieces to prevent white from escaping without moving forever. I am not sure if its better or worse to favor black in these situations.
I don't think these modifications will allow you to achieve shorter games. I think by removing the draw fort strategy you cripple a large part of the Fetlar strategy and produce a completely new variant that won't have any predictable expectation of balance and so perhaps Fetlar is not particularly well suited for what you wish to accomplish with your tournament.
EDIT: just saw that you responded before I posted this. Well yes i suppose it may be a little late now
but maybe something to take with a grain of salt for your next AI tournament!