Im not sure if this will work in your situation but I just called last night and asked for it (However I have been a customer for a year and am on a 3 year contract already). The first rep told me it was not possible since I live in Ontario, so I politely said "ok, thank you" and called again.
When I got the second rep I explained to him that other people are able to get it in Ontario and that I shouldn't have to pay more just because I live in a different province. I also said that I am paying $10 a month more for less and that it doesn't make sense to pay over a hundred a year for less. After saying this (politely) he agreed to give me the Sask 55 plan.
So yes it is possible to get the plan if you live in Ontario, what I would do is call retentions and explain to them what you want to do. If they say no phone back a few times and keep trying. If after 5ish tries the answer is still no its probably because you aren't a customer yet, so at that point I would try finding a nice plan you can get and then calling them in a month or two and trying again.
Hope this helps!
EDIT: I also just called back now and asked if I could have caller id, they said that I couldn't have it for free but I could have it for $5 instead of 8. So now my bill is $60 before taxes with this:
5 gig data
After 5 weekends/evenings free
So try calling them and hopefully you can get something like this