You're correct - the train is closed during Wishes and the parade. So here's my strategy:
- During crazy-crowded times (July 4th, Christmas week, NYE) they will actually open backstage areas. One backstage area is right before the strip of stores connected to the MSB. You could go backstage and it leads you to the area at front of The Plaza ice cream parlor.
- Follow the tape and stay to your right. Sounds simple enough, but many do not listen
- Stay away from the castle. The castle and Main Street are the most popular locations for the parades and Main Street gets incredibly crowded. Most parades snake around the left side of the park (Liberty Square, Adventureland and down Main Street.) During parades, try and stay in Tomorrowland, Fantasyland or Frontierland. Wait times will be lower during the parades and firework show, so it's a great opportunity to head to Space, Thunder or Splash Mountain. By the time you are done with the ride(s), the parade will be done.
- The parades are perfectly timed and synchronized. Disney CMs have actually begun allowing guests to cross the parade route during stoppages mid-parade. The areas to cross the parade (should you choose to) are by the Bear Jamboree (I believe), and by the little island at the front of the park (the only two I have experienced.)
- The parades begin at Frontierland (near the railroad) and end by Main Street. You can see the route on the map. This means that you could stay to the back and the right side of the park to avoid the route.
- If you're stuck in Frontierland, there are a lot of unknown connections to other lands that you could use to your advantage.
- The parade crossing I alluded to above allows you to get to a corridor which has bathrooms and leads to Adventureland. If you can walk fast, you'll beat the parade to Main Street and get out of there! Also, many stores on the parade route are connected. For example, you can walk most of the route in Frontierland from inside the stores.
- There is also a bridge (near the castle) that goes from Liberty Square to the entrance of Adventureland, then another that will lead you to the front of the Crystal Palace.
- If you can get to Main Street, stay on the Casey's side of the street (looking at the castle LEFT, looking at the entrance RIGHT) There is a souvenir store that spans the length of the street. You can enter it and walk straight through - It starts with a sports store, then you walk through the clothing, etc. then through the toys, and then through the houseware items.. then BOOM you're at the front of the park.
- There's a smoking section near Liberty Square and the back of the castle. The path is seldom-used and will bring you to the front of the castle.
That's all I could think of now. So to summarize:
- Stay away from the castle
- Stay in Tomorrowland and the back of the park
- Use the time to go on rides. The wait time will be lower and by the time you are done the parade will be over.
- Use connecting stores (along Frontierland and Main Street) to get away from crowds and to your destination
- Look for areas where CMs are letting you cut through the parade.