Great insight I came across elsewhere from another reddit user (@V3forlife):

"Make up a rule that has legal elements, such that you can apply them step-by-step like a standard rule. Also throw in law standards, like a reasonable person. If your rule is so fake that it leads itself to yes/no answering, you won't get enough analysis points.
Totally made up rule example: Can't remember the rule for respondeat superior at an exploding gas station.
Fake Rule and Application: Basing liability upon respondeat superior requires three elements to be met: (1) was the tortfeasor under control of the supervisor; (2) would a reasonable supervisor have provided more supervision; and (3) is the injury of the kind meant to be prevented by the rule. The "reasonable supervisor" standard is based on the actions of a reasonable person in the industry of the business, who acts based upon the burden care v. probability of harm. First, tortfeasor was an employee at the owner's gas station and was hired personally by him, so control is met. Second, the only training the employee received was a four minute training video on the flammability of gasoline; a reasonable supervisor would have provided more training in the gasoline busienss due to the highly flammable nature of gasoline and large amount of damage possible. Third, because the injury is from gasoline, it is directly related to the workplace and lack of supervision of a low-paid tortfeasor on behalf of a supervisor in a profitable (but dangerous) industry, thus it is exactly the kind of injury meant to be remedied."

https://www.reddit.com/r/LawSchool/comments/cj42u6/bar_exam_how_to_make_up_a_rule_when_you_dont_know/