If I had a rural office would Stark apply?

There is a rural exception in the Stark law and regulations. Specifically, section 1877(d)(2) of the Social Security Act provides that designated health services furnished by an entity in a rural area are not considered to be an ownership or investment interest otherwise prohibited under Stark if substantially all of the designated health services furnished by the entity are to individuals residing in a rural area.

Section 1886(d)(2)(D) of the Social Security Act defines the term "rural area" as any area outside a Metropolitan Statistical Area (as defined by the U.S. Office of Management and Budget). Thus, your understanding of the exception is generally correct.