Is it possible to have sleep paralysis while sleepwalking?
While it is hard to completely rule out this convergence ever happening (perhaps cases haven't been reported), it is highly unlikely due to the specific stages of the ultradian sleep cycle at which sleep walking and sleep paralysis occur [Ref. 1]. Sleep walking during non-REM sleep would have to continue through the REM stage in order to see intrusion of sleep paralysis that occurs at the exit of REM to wake [Ref. 2].  

A key feature of REM sleep is deep muscle atonia that paralyzes the body and prevents among other things one from acting out dreams [Ref .3]. Thus, if a person sleep walking were able to enter REM before returning to bed, the sleep walking / other unconscious motion itself would cease.

I do question your reasoning that the combination of these two parasomnias would result in being:


  consciously aware of yourself and
  your surroundings while you are also unconsciously moving about,
  outside of your conscious control.


because the intrusion of sleep paralysis would in fact lead to muscle atonia and prevent one moving about. This is not to say that terrible things have not occurred where muscle atonia has failed while the subject remains asleep/unconscious; this falls under the fascinating category of REM-behavior disorders (where people act our their dreams - including violently hurting themselves and their partners), which judging by your question I think you will find interesting! [Ref. 4].

References:
[Ref. 1]: sleep stages
[Ref. 2]: sleep paralysis
[Ref. 3]: muscle atonia
[Ref. 4]: rem-behavior disorder