Point of clarification. No protection from Geneva conventions is not lack of any protection. Geneva conventions forbade certain acts and weapons, regardless of the target. This includes torture and sexual violence. Combatant status also doesn’t preclude other protections like fundamental human rights protections. You still shouldn’t be summarily executed or tortured due to combatant status.

Using subterfuge and deception is perfectly lawful. Otherwise basic stuff like camouflage would be war crimes. But that’s not what unlawful combatant is about. Terrorism is always unlawful, for example, because the main target is civilians in order to cause, well, terror. It doesn’t matter if the terrorists were using their club’s pin badge that day or not. Similarly, if you are a civilian in civilian clothes and take up a rifle to shoot at a party in an armed conflict, congratulations, you just became a lawful combatant. You became a lawful combat target, your Hawaiian shirt notwithstanding.

You’re an unlawful combatant if you’re targeting protected classes, like civilians, wounded, prisoners, health care personnel, etc. Even if you’re clearly in your new uniform with fresh new tags. Clothing is a secondary aspect. The main defining feature is always role and behavior. Like, creating a combat unit of snipers specialized in targeting journalists, that would be a group of unlawful combatants.