I'd toss the pocket mask to save space; AHA is pushing CPR w/o ventilations now. If you want to do the ventilations, there are more compact barrier devices that will work in an emergency (Google keychain pocket mask).
All good thoughts on making additions to a bag, however I want to point out one thing I believe to be important. From what I understand, as conveyed to me by the Wilderness Medical Institute, the AHA is pushing CPR w/o ventilations for the general untrained public in urban settings where EMS is less than 3 or 4 minutes away. Studies found that most people did not know the proper number of ventilations to give or they did not have proper technique for establishing the airway or they just plain old blew too hard and induced vomiting, so rather than making it too complicated the AHA finds that chest compressions alone for the time it takes for help to arrive in an urban setting are sufficient to circulate the still-somewhat-oxygenated-blood through the system.
Anywhere you may need a ditch bag EMS is most likely more than 3 or 4 minutes away.
The fold up pocket style is fine too but if you have the space the inflatable mask offers a more comfortable and cleaner solution as well as having the capability of hooking into a bag if you have one.
Brian