I wouldn't worry too much about a pocket mask, if you are feeling exceptionally Ricky Rescue go with the BVM.
As stated above, compressions are the way to go anymore. Especially with witnessed arrests, your oxygen hemoglobin saturation is enough that you can go upwards of 5 minutes without any serious airway interventions. Position the head properly while doing CPR and you will still get air movement with the compressions, albeit minimal.
Even for us medics we are only tossing in an airway device, OPA or NPA and applying a face mask with 15 liters of O2 for the first 4-5 minutes of an arrest anyway. We focus on early and uninterrupted chest compressions, defibrillation, and IV access for arrest meds, all before we even consider any advanced airways or manual ventilation. They are even frowning on field intubations anymore because of how long they take while no CPR is being performed. They are pushing LMA's and King's on us in a big way because they can be done without halting compressions and are damn near idiot proof.