I haven't done it yet, but I would assume you should be able to bubble heal if needed, assuming you didn't build up any aggro on your lowbies. You could also respec into Holy tree just for this and pick up 5/5 Spiritual Focus. That with concetration aura will give you 100% uninterrupted heals. I have the trinket and I may do this too just for backup and to help when boosting in higher level instances.