Depends on where you are going in Canada... If a major center (Toronto, Montreal, Vancouver, Calgary etc.) you should be able to find a bullion store... If you are going to a small town such as Quesnel, BC or Flin Flon MB, you will be out of luck.
Big dealers will accept USD but CAD will usually be preferred.
Crossing the border with maples will be straightforward but depending on how much you have you may have to declare... You have to declare cash that exceeds $10,000. Bullion is considered as cash for these purposes... BTW, you will also have to declare anything over $10,000 CAD (approx $7K US) when you come into Canada. It is not taxable or subject to duty but the government wants to know about large cash transfers across a border and if you have a large sum, anticipate being asked why and whether you are about to traffic in illicit goods. Additionally, travelling with a large "wad" of cash to and from the border/airport can subject you to civil forfeiture where you can have your cash seized by a police officer and you have to sue for its return. The government doesn't want you using cash.
With all of that said, you should consider purchasing in the US... if you don't have a local bullion dealer, there are plenty of online dealers e.g. APMEX
that will sell bullion at competitive prices. There is no added value or reduced cost in purchasing Maples in Canada. Silver Maples here are usually within a dollar or so of equivalent Silver Eagles... Again very similar to online US dealers.