Hello Again,The ferry from Bar Harbour and visit to the park is a great choice. You'll have a long haul from there to Cape Breton. I'd suggest you head there after you've finished and in an RV it will be 6 to 8 hours. I think the Cabot Trail is a must and the area is filled with music for the entire summer. From old time fiddle dances to festivals. There will be tourist info stations that will fill you in on the music and highlights of the area.
I'd suggest you head back via PEI by catching the ferry in Pictou. You can then come back through New Brunswick via the fixed link.
I'm in the Middle East at the moment but I will try and source a web site that is provided by the government. When I find it I'll post it here for you.
I'll give this a bit more thought and try to help with things I think you should see.
Jim