I like the idea of not having the 3 spawns to be there initially, canadians deserve some time to prepare. Dummy flags would be the best idea. (I think there are some reasons for trucks and APC to exist rather than just being armoured machine gun?)
I have another idea,
That is, to give Canadians a temporory "main" somewhere else when mortar battery is lost, here are my arguments
1. Canadian armour shouldn't be cut-off just because of a flanking action, it just don't make sense you can cut off enemy armour with simply infantry.
2. The temporory main should exist only when the canadians still hold the 2 flags in the town. So it would be the fault of the canadians if they can't hold the rest of the flags when a backcap occurs.
3. Give the Germans some heavy weapons when they captured the mortar battery, such as PaK guns and panzerschrecks to defend their gains against canadians attempting to recap.
The only problem that this idea would cause is that the Canadians would have a lot of armour when mortar battery is recap very quickly afterwards, which makes the map imbalanced.