Here's the rules as they stand now. GURPS Martial Arts, p. 97, says
The GM should be generous about substituting feints for attacks, too. An All-Out Attack (Feint) is just an All-Out Attack (Double) that trades the first attack for a feint, so there's no reason why a fighter couldn't reverse the order: attack first and then feint to benefit a later attack. Other alternatives include using All-Out Attack (Determined) to feint at +4 and All-Out Attack (Long) to feint a distant foe.
And on Martial Arts, p. 127, discussing multiple attacks:
A fighter can trade melee attacks for feints (see Feint, p. B365) on a one-for one basis. Modifiers for maneuvers and attack options do affect skill for this purpose; e.g., a feint during a Rapid Strike is at -6. A warrior can use Move and Attack to "Move and Feint," but at -4 and with a skill limit of 9, it's self-defeating.So we're most of the way there already. What remains is to go through the maneuvers and attack options to see what's compatible with the Feint attack option, and to figure out how opting for a Beat or a Ruse would make things any different.
Already, by RAW, these maneuvers are compatible with Feint:
All-Out Attack (Double)
All-Out Attack (Determined)
All-Out Attack (Long)
Move and Attack -- this is "self-defeating" with a skill cap of 9, but see Heroic Charge, below
And Rapid Strike is already compatible by RAW.
Here are my proposals for handling the rest:
All-Out Attack (Strong): by RAW, an ordinary AOA (Strong) maneuver gets you +2 to damage, or +1 per die if that is better. This is approximately equivalent to +2 to Strength. I don't how increasing the power of a Feint would help to fool your opponent, so I say this one applies only to a Beat (MA p. 100).
Committed Attack (Determined): +2 to your Feint roll. You are penalized on Active Defenses as usual. This may not be your best option if you are a single-weapon fighter and you rely on your Parry for defense, but it could be effective for a two-weapon or unarmed fighter.
Committed Attack (Strong): Only available with a Beat. You get +1 to your roll.
Defensive Attack: you take -2 to your Quick Contest roll, and gain all the benefits of Defensive Attack as usual.
Wait: a Feint is not compatible with a Stop Hit (MA p. 108).
Deceptive Attack: For every -2 penalty on the Quick Contest roll you take, your opponent loses an additional -1 to defenses on your following attack. If you do not win the Quick Contest, your Deceptive Attack gains you nothing. You can also use Deceptive Attack on a Defensive Feint to impose a penalty to your opponent's next attack roll, but this will seldom be worthwhile.
Hit Locations: you gain nothing by targeting a hit location with a Feint, so this option is not so much incompatible as useless.
Dual-Weapon Attack: You may apply the Feint option to either half of a Dual-Weapon Attack. If the first attack is a Feint, only the remaining attacks in this round benefit from it.
Telegraphic Attack: Not compatible with Feint.
Slam and Shove: Not compatible with Feint.
Defensive Grip, Reversed Grip, Tip Slash: Compatible with Feint.
Extra Effort: Flurry of Blows, Giant Step, Great Lunge, and Heroic Charge are all compatible with Feint. In fact, Heroic Charge is about the only way to make a Feint work with a Move and Attack maneuver. Since a Feint does not make a weapon unready, Rapid Recovery is irrelevant.
Beats and Ruses: Except as noted above, Beats and Ruses are handled just like Feints.
I don't think there are any other problem combat options. Please let me know if you think I've missed anything.