If there is a cortege on a dual carriageway I think it is acceptable to pass it. On a single lane road I think it would be disrespectful. The other day though I got stuck behind a procession driving in the outside lane of the dual carriageway into town. 
I've said before, on this topic, that we live on the route between the village church and the cemetery so have this problem quite often. All the people in the village stay in the queue and it is bound to happen when I'm running late!
My maternal grandparents, great grandparents, an aunt and a couple of uncles are buried in South Cemetery and I have yet to find the family grave when I have been on my own.
Our road is often quite a stressful drive as there are also 3 farms, 4 stables, a school and a huge new estate between us and town with all the inevitable delays they bring.
Congratulations on the new addition Vegas 