QUESTION:
How was the design of the rocker-bogie system finalized? Specifically, how
were the various arm lengths and pivots points chosen to maximize the
rover's mobility?

ANSWER from David Dubov:
The footprint of the rover was determined by the size of the vehicle which
could be safely stowed on the lander petal. Within this constraint, the
rocker-bogie system for Sojourner was adapted from the system implemented on
Rocky 4 (an early technology demonstration vehicle). That system (6 evenly
spaced wheels, allowing for more than a wheel diameter of obstacle
traversal, nearly symmetrical in capability for forward/backward motions,
unusual rock configuration needed for hangup, etc.) met all requirements for
the Sojourner vehicle mission. Pivot joint stops were determined by
potential for interference with other portions of the vehicle structure
(solar panel, wire bundles, etc.).