You may be surprised at what you can get, I think that mini greenhouse should buy you a fair amount of time, especially if you can try to keep it warm in there at night. Got a big corn pot? Boil up a few buckets worth of water at night time and put them in the little tent. Make sure to cover them if humidity is a factor. What's the long term forecast look like for Saskatchewan now?
I usually don't have to worry about any killing-strength frost until about the first week of October, though we get the odd late September shocker. It's the rain and humidity that can destroy us here in the east. We'll get days and days of grey rainy weather and 80-100% humidity, often with the odd warm sunny day thrown in just to help out the mold.
I top most of them to get smaller buds to fight it.
I don't cover anything out there. It would be a nice option, but my plants are spread out in the bush. I'd have to build too many structures, and then I'd be scared of having them spotted easily. Your greenhouse in the garden looks less conspicuous than a greenhouse in the forest.
I'll throw some pics up on my thread tomorrow to show how mine are doing now. I'm about a week behind last year, but they seem to be taking off now. I've had a lot of sun this past week. It was over 30 degrees today, near 40 with the humidex.