re: Could the Phoenix spacecraft carry out a 'bonus' experiment/activity?
IMO, The Surveyor 6 manouevre was more intended to explore the mechanics of launching from the Moon's surface, in preparation for the Apollo programme. Issues such as ballistic dust and rock fragments, stability of the Lunar surface under the exhaust jet were important unknowns.
Although this did give some interesting stereo imaging capability, I think the real desire was to be able to image the primary landing spot itself from a nearby location to see if any major disruption had occurred.
Without such a strong driver, I think the risk of "tripping" or otherwise destabilising the craft would preclude the manouevre...