i solo'ed it with my lvl 60 whm. should be possible. but (second) last boss in castrum will be a bit difficult (you have to manage some stuff while being attacked wich will cancel your interactions) and there was one boss in the later dungeon with a lot of adds with knockback abilities wich is really a pain, but it is all doable if played well.

i would say you should search one other person who will do the dungeons with you together unsynched and waits for your cutscenes.